/**
* Print an alignment map in a concise representation. Edges are given as two numbers separated by
* '>'. They are chained together where possible, or separated by spaces where disjoint or
* branched.
*
* <p>Note that more concise representations may be possible. Examples:
* <li>1>2>3>1
* <li>1>2>3>2 4>3
*
* @param alignment The input function, as a map (see {@link
* AlignmentTools#alignmentAsMap(AFPChain)})
* @param identity An identity-like function providing the isomorphism between the codomain of
* alignment (of type <T>) and the domain (type <S>).
* @return
*/
public static <S, T> String toConciseAlignmentString(Map<S, T> alignment, Map<T, S> identity) {
// Clone input to prevent changes
Map<S, T> alig = new HashMap<S, T>(alignment);
// Generate inverse alignment
Map<S, List<S>> inverse = new HashMap<S, List<S>>();
for (Entry<S, T> e : alig.entrySet()) {
S val = identity.get(e.getValue());
if (inverse.containsKey(val)) {
List<S> l = inverse.get(val);
l.add(e.getKey());
} else {
List<S> l = new ArrayList<S>();
l.add(e.getKey());
inverse.put(val, l);
}
}
StringBuilder str = new StringBuilder();
while (!alig.isEmpty()) {
// Pick an edge and work upstream to a root or cycle
S seedNode = alig.keySet().iterator().next();
S node = seedNode;
if (inverse.containsKey(seedNode)) {
node = inverse.get(seedNode).iterator().next();
while (node != seedNode && inverse.containsKey(node)) {
node = inverse.get(node).iterator().next();
}
}
// Now work downstream, deleting edges as we go
seedNode = node;
str.append(node);
while (alig.containsKey(node)) {
S lastNode = node;
node = identity.get(alig.get(lastNode));
// Output
str.append('>');
str.append(node);
// Remove edge
alig.remove(lastNode);
List<S> inv = inverse.get(node);
if (inv.size() > 1) {
inv.remove(node);
} else {
inverse.remove(node);
}
}
if (!alig.isEmpty()) {
str.append(' ');
}
}
return str.toString();
}
/**
* Takes a potentially non-sequential alignment and guesses a sequential version of it. Residues
* from each structure are sorted sequentially and then compared directly.
*
* <p>The results of this method are consistent with what one might expect from an identity
* function, and are therefore useful with {@link #getSymmetryOrder(Map, Map identity, int,
* float)}.
*
* <ul>
* <li>Perfect self-alignments will have the same pre-image and image, so will map X->X
* <li>Gaps and alignment errors will cause errors in the resulting map, but only locally.
* Errors do not propagate through the whole alignment.
* </ul>
*
* <h4>Example:</h4>
*
* A non sequential alignment, represented schematically as
*
* <pre>
* 12456789
* 78912345</pre>
*
* would result in a map
*
* <pre>
* 12456789
* 12345789</pre>
*
* @param alignment The non-sequential input alignment
* @param inverseAlignment If false, map from structure1 to structure2. If true, generate the
* inverse of that map.
* @return A mapping from sequential residues of one protein to those of the other
* @throws IllegalArgumentException if the input alignment is not one-to-one.
*/
public static Map<Integer, Integer> guessSequentialAlignment(
Map<Integer, Integer> alignment, boolean inverseAlignment) {
Map<Integer, Integer> identity = new HashMap<Integer, Integer>();
SortedSet<Integer> aligned1 = new TreeSet<Integer>();
SortedSet<Integer> aligned2 = new TreeSet<Integer>();
for (Entry<Integer, Integer> pair : alignment.entrySet()) {
aligned1.add(pair.getKey());
if (!aligned2.add(pair.getValue()))
throw new IllegalArgumentException(
"Alignment is not one-to-one for residue "
+ pair.getValue()
+ " of the second structure.");
}
Iterator<Integer> it1 = aligned1.iterator();
Iterator<Integer> it2 = aligned2.iterator();
while (it1.hasNext()) {
if (inverseAlignment) { // 2->1
identity.put(it2.next(), it1.next());
} else { // 1->2
identity.put(it1.next(), it2.next());
}
}
return identity;
}
/**
* Takes an AFPChain and replaces the optimal alignment based on an alignment map
*
* <p>Parameters are filled with defaults (often null) or sometimes calculated.
*
* <p>For a way to create a new AFPChain, see {@link AlignmentTools#createAFPChain(Atom[], Atom[],
* ResidueNumber[], ResidueNumber[])}
*
* @param afpChain The alignment to be modified
* @param alignment The new alignment, as a Map
* @throws StructureException if an error occurred during superposition
* @see AlignmentTools#createAFPChain(Atom[], Atom[], ResidueNumber[], ResidueNumber[])
*/
public static AFPChain replaceOptAln(
AFPChain afpChain, Atom[] ca1, Atom[] ca2, Map<Integer, Integer> alignment)
throws StructureException {
// Determine block lengths
// Sort ca1 indices, then start a new block whenever ca2 indices aren't
// increasing monotonically.
Integer[] res1 = alignment.keySet().toArray(new Integer[0]);
Arrays.sort(res1);
List<Integer> blockLens = new ArrayList<Integer>(2);
int optLength = 0;
Integer lastRes = alignment.get(res1[0]);
int blkLen = lastRes == null ? 0 : 1;
for (int i = 1; i < res1.length; i++) {
Integer currRes = alignment.get(res1[i]); // res2 index
assert (currRes
!= null); // could be converted to if statement if assertion doesn't hold; just modify
// below as well.
if (lastRes < currRes) {
blkLen++;
} else {
// CP!
blockLens.add(blkLen);
optLength += blkLen;
blkLen = 1;
}
lastRes = currRes;
}
blockLens.add(blkLen);
optLength += blkLen;
// Create array structure for alignment
int[][][] optAln = new int[blockLens.size()][][];
int pos1 = 0; // index into res1
for (int blk = 0; blk < blockLens.size(); blk++) {
optAln[blk] = new int[2][];
blkLen = blockLens.get(blk);
optAln[blk][0] = new int[blkLen];
optAln[blk][1] = new int[blkLen];
int pos = 0; // index into optAln
while (pos < blkLen) {
optAln[blk][0][pos] = res1[pos1];
Integer currRes = alignment.get(res1[pos1]);
optAln[blk][1][pos] = currRes;
pos++;
pos1++;
}
}
assert (pos1 == optLength);
// Create length array
int[] optLens = new int[blockLens.size()];
for (int i = 0; i < blockLens.size(); i++) {
optLens[i] = blockLens.get(i);
}
return replaceOptAln(afpChain, ca1, ca2, blockLens.size(), optLens, optAln);
}
/** @see #toConciseAlignmentString(Map, Map) */
public static Map<Integer, Integer> fromConciseAlignmentString(String string) {
Map<Integer, Integer> map = new HashMap<Integer, Integer>();
boolean matches = true;
while (matches) {
Pattern pattern = Pattern.compile("(\\d+)>(\\d+)");
Matcher matcher = pattern.matcher(string);
matches = matcher.find();
if (matches) {
Integer from = Integer.parseInt(matcher.group(1));
Integer to = Integer.parseInt(matcher.group(2));
map.put(from, to);
string = string.substring(matcher.end(1) + 1);
}
}
return map;
}
/**
* identify additional groups that are not directly attached to amino acids.
*
* @param mc {@link ModifiedCompound}.
* @param chain a {@link Chain}.
* @return a list of added groups.
*/
private void identifyAdditionalAttachments(
ModifiedCompound mc, List<Group> ligands, Map<String, Chain> mapChainIdChain) {
if (ligands.isEmpty()) {
return;
}
// TODO: should the additional groups only be allowed to the identified
// ligands or both amino acids and ligands? Currently only on ligands
// ligands to amino acid bonds for same modification of unknown category
// will be combined in mergeModComps()
// TODO: how about chain-chain links?
List<Group> identifiedGroups = new ArrayList<Group>();
for (StructureGroup num : mc.getGroups(false)) {
Group group;
try {
// String numIns = "" + num.getResidueNumber();
// if (num.getInsCode() != null) {
// numIns += num.getInsCode();
// }
ResidueNumber resNum = new ResidueNumber();
resNum.setChainId(num.getChainId());
resNum.setSeqNum(num.getResidueNumber());
resNum.setInsCode(num.getInsCode());
// group = chain.getGroupByPDB(numIns);
group = mapChainIdChain.get(num.getChainId()).getGroupByPDB(resNum);
} catch (StructureException e) {
logger.error("Exception: ", e);
// should not happen
continue;
}
identifiedGroups.add(group);
}
int start = 0;
int n = identifiedGroups.size();
while (n > start) {
for (Group group1 : ligands) {
for (int i = start; i < n; i++) {
Group group2 = identifiedGroups.get(i);
if (!identifiedGroups.contains(group1)) {
List<Atom[]> linkedAtoms =
StructureUtil.findAtomLinkages(group1, group2, false, bondLengthTolerance);
if (!linkedAtoms.isEmpty()) {
for (Atom[] atoms : linkedAtoms) {
mc.addAtomLinkage(
StructureUtil.getStructureAtomLinkage(atoms[0], false, atoms[1], false));
}
identifiedGroups.add(group1);
break;
}
}
}
}
start = n;
n = identifiedGroups.size();
}
}
/**
* Creates a Map specifying the alignment as a mapping between residue indices of protein 1 and
* residue indices of protein 2.
*
* <p>For example,
*
* <pre>
* 1234
* 5678</pre>
*
* becomes
*
* <pre>
* 1->5
* 2->6
* 3->7
* 4->8</pre>
*
* @param afpChain An alignment
* @return A mapping from aligned residues of protein 1 to their partners in protein 2.
* @throws StructureException If afpChain is not one-to-one
*/
public static Map<Integer, Integer> alignmentAsMap(AFPChain afpChain) throws StructureException {
Map<Integer, Integer> map = new HashMap<Integer, Integer>();
if (afpChain.getAlnLength() < 1) {
return map;
}
int[][][] optAln = afpChain.getOptAln();
int[] optLen = afpChain.getOptLen();
for (int block = 0; block < afpChain.getBlockNum(); block++) {
for (int pos = 0; pos < optLen[block]; pos++) {
int res1 = optAln[block][0][pos];
int res2 = optAln[block][1][pos];
if (map.containsKey(res1)) {
throw new StructureException(
String.format("Residue %d aligned to both %d and %d.", res1, map.get(res1), res2));
}
map.put(res1, res2);
}
}
return map;
}
/**
* Uses two sequences each with a corresponding structure to create an AFPChain corresponding to
* the alignment. Provided only for convenience since FastaReaders return such maps.
*
* @param sequences A Map containing exactly two entries from sequence names as Strings to gapped
* ProteinSequences; the name is ignored
* @see #fastaToAfpChain(ProteinSequence, ProteinSequence, Structure, Structure)
* @throws StructureException
*/
public static AFPChain fastaToAfpChain(
Map<String, ProteinSequence> sequences, Structure structure1, Structure structure2)
throws StructureException {
if (sequences.size() != 2) {
throw new IllegalArgumentException(
"There must be exactly 2 sequences, but there were " + sequences.size());
}
if (structure1 == null || structure2 == null) {
throw new IllegalArgumentException("A structure is null");
}
List<ProteinSequence> seqs = new ArrayList<ProteinSequence>();
List<String> names = new ArrayList<String>(2);
for (Map.Entry<String, ProteinSequence> entry : sequences.entrySet()) {
seqs.add(entry.getValue());
names.add(entry.getKey());
}
return fastaToAfpChain(seqs.get(0), seqs.get(1), structure1, structure2);
}
/**
* Applies an alignment k times. Eg if alignmentMap defines function f(x), this returns a function
* f^k(x)=f(f(...f(x)...)).
*
* <p>To allow for functions with different domains and codomains, the identity function allows
* converting back in a reasonable way. For instance, if alignmentMap represented an alignment
* between two proteins with different numbering schemes, the identity function could calculate
* the offset between residue numbers, eg I(x) = x-offset.
*
* <p>When an identity function is provided, the returned function calculates f^k(x) = f(I( f(I(
* ... f(x) ... )) )).
*
* @param <S>
* @param <T>
* @param alignmentMap The input function, as a map (see {@link
* AlignmentTools#alignmentAsMap(AFPChain)})
* @param identity An identity-like function providing the isomorphism between the codomain of
* alignmentMap (of type <T>) and the domain (type <S>).
* @param k The number of times to apply the alignment
* @return A new alignment. If the input function is not automorphic (one-to-one), then some
* inputs may map to null, indicating that the function is undefined for that input.
*/
public static <S, T> Map<S, T> applyAlignment(Map<S, T> alignmentMap, Map<T, S> identity, int k) {
// This implementation simply applies the map k times.
// If k were large, it would be more efficient to do this recursively,
// (eg f^4 = (f^2)^2) but k will usually be small.
if (k < 0) throw new IllegalArgumentException("k must be positive");
if (k == 1) {
return new HashMap<S, T>(alignmentMap);
}
// Convert to lists to establish a fixed order
List<S> preimage = new ArrayList<S>(alignmentMap.keySet()); // currently unmodified
List<S> image = new ArrayList<S>(preimage);
for (int n = 1; n < k; n++) {
// apply alignment
for (int i = 0; i < image.size(); i++) {
S pre = image.get(i);
T intermediate = (pre == null ? null : alignmentMap.get(pre));
S post = (intermediate == null ? null : identity.get(intermediate));
image.set(i, post);
}
}
Map<S, T> imageMap = new HashMap<S, T>(alignmentMap.size());
// TODO handle nulls consistently.
// assure that all the residues in the domain are valid keys
/*
for(int i=0;i<preimage.size();i++) {
S pre = preimage.get(i);
T intermediate = (pre==null?null: alignmentMap.get(pre));
S post = (intermediate==null?null: identity.get(intermediate));
imageMap.put(post, null);
}
*/
// now populate with actual values
for (int i = 0; i < preimage.size(); i++) {
S pre = preimage.get(i);
// image is currently f^k-1(x), so take the final step
S preK1 = image.get(i);
T postK = (preK1 == null ? null : alignmentMap.get(preK1));
imageMap.put(pre, postK);
}
return imageMap;
}
/**
* Tries to detect symmetry in an alignment.
*
* <p>Conceptually, an alignment is a function f:A->B between two sets of integers. The function
* may have simple topology (meaning that if two elements of A are close, then their images in B
* will also be close), or may have more complex topology (such as a circular permutation). This
* function checks <i>alignment</i> against a reference function <i>identity</i>, which should
* have simple topology. It then tries to determine the symmetry order of <i>alignment</i>
* relative to <i>identity</i>, up to a maximum order of <i>maxSymmetry</i>.
*
* <p><strong>Details</strong><br>
* Considers the offset (in number of residues) which a residue moves after undergoing <i>n</i>
* alternating transforms by alignment and identity. If <i>n</i> corresponds to the intrinsic
* order of the alignment, this will be small. This algorithm tries increasing values of <i>n</i>
* and looks for abrupt decreases in the root mean squared offset. If none are found at
* <i>n</i><=maxSymmetry, the alignment is reported as non-symmetric.
*
* @param alignment The alignment to test for symmetry
* @param identity An alignment with simple topology which approximates the sequential
* relationship between the two proteins. Should map in the reverse direction from alignment.
* @param maxSymmetry Maximum symmetry to consider. High values increase the calculation time and
* can lead to overfitting.
* @param minimumMetricChange Percent decrease in root mean squared offsets in order to declare
* symmetry. 0.4f seems to work well for CeSymm.
* @return The order of symmetry of alignment, or 1 if no order <= maxSymmetry is found.
* @see IdentityMap For a simple identity function
*/
public static int getSymmetryOrder(
Map<Integer, Integer> alignment,
Map<Integer, Integer> identity,
final int maxSymmetry,
final float minimumMetricChange) {
List<Integer> preimage = new ArrayList<Integer>(alignment.keySet()); // currently unmodified
List<Integer> image = new ArrayList<Integer>(preimage);
int bestSymmetry = 1;
double bestMetric = Double.POSITIVE_INFINITY; // lower is better
boolean foundSymmetry = false;
if (debug) {
logger.trace("Symm\tPos\tDelta");
}
for (int n = 1; n <= maxSymmetry; n++) {
int deltasSq = 0;
int numDeltas = 0;
// apply alignment
for (int i = 0; i < image.size(); i++) {
Integer pre = image.get(i);
Integer intermediate = (pre == null ? null : alignment.get(pre));
Integer post = (intermediate == null ? null : identity.get(intermediate));
image.set(i, post);
if (post != null) {
int delta = post - preimage.get(i);
deltasSq += delta * delta;
numDeltas++;
if (debug) {
logger.debug("%d\t%d\t%d\n", n, preimage.get(i), delta);
}
}
}
// Metrics: RMS compensates for the trend of smaller numDeltas with higher order
// Not normalizing by numDeltas favors smaller orders
double metric = Math.sqrt((double) deltasSq / numDeltas); // root mean squared distance
if (!foundSymmetry && metric < bestMetric * minimumMetricChange) {
// n = 1 is never the best symmetry
if (bestMetric < Double.POSITIVE_INFINITY) {
foundSymmetry = true;
}
bestSymmetry = n;
bestMetric = metric;
}
// When debugging need to loop over everything. Unneeded in production
if (!debug && foundSymmetry) {
break;
}
}
if (foundSymmetry) {
return bestSymmetry;
} else {
return 1;
}
}
/**
* Identify a set of modifications in a a list of chains.
*
* @param chains query {@link Chain}s.
* @param potentialModifications query {@link ProteinModification}s.
*/
public void identify(
final List<Chain> chains, final Set<ProteinModification> potentialModifications) {
if (chains == null) {
throw new IllegalArgumentException("Null structure.");
}
if (potentialModifications == null) {
throw new IllegalArgumentException("Null potentialModifications.");
}
reset();
if (potentialModifications.isEmpty()) {
return;
}
Map<String, Chain> mapChainIdChain = new HashMap<String, Chain>(chains.size());
residues = new ArrayList<Group>();
List<Group> ligands = new ArrayList<Group>();
Map<Component, Set<Group>> mapCompGroups = new HashMap<Component, Set<Group>>();
for (Chain chain : chains) {
mapChainIdChain.put(chain.getChainID(), chain);
List<Group> ress = StructureUtil.getAminoAcids(chain);
// List<Group> ligs = chain.getAtomLigands();
List<Group> ligs = StructureTools.filterLigands(chain.getAtomGroups());
residues.addAll(ress);
residues.removeAll(ligs);
ligands.addAll(ligs);
addModificationGroups(potentialModifications, ress, ligs, mapCompGroups);
}
if (residues.isEmpty()) {
String pdbId = "?";
if (chains.size() > 0) {
Structure struc = chains.get(0).getParent();
if (struc != null) pdbId = struc.getPDBCode();
}
logger.warn(
"No amino acids found for {}. Either you did not parse the PDB file with alignSEQRES records, or this record does not contain any amino acids.",
pdbId);
}
List<ModifiedCompound> modComps = new ArrayList<ModifiedCompound>();
for (ProteinModification mod : potentialModifications) {
ModificationCondition condition = mod.getCondition();
List<Component> components = condition.getComponents();
if (!mapCompGroups.keySet().containsAll(components)) {
// not all components exist for this mod.
continue;
}
int sizeComps = components.size();
if (sizeComps == 1) {
processCrosslink1(mapCompGroups, modComps, mod, components);
} else {
processMultiCrosslink(mapCompGroups, modComps, mod, condition);
}
}
if (recordAdditionalAttachments) {
// identify additional groups that are not directly attached to amino acids.
for (ModifiedCompound mc : modComps) {
identifyAdditionalAttachments(mc, ligands, mapChainIdChain);
}
}
mergeModComps(modComps);
identifiedModifiedCompounds.addAll(modComps);
// record unidentifiable linkage
if (recordUnidentifiableModifiedCompounds) {
recordUnidentifiableAtomLinkages(modComps, ligands);
recordUnidentifiableModifiedResidues(modComps);
}
}
