/**
* Checks that the alignment given by afpChain is sequential. This means that the residue indices
* of both proteins increase monotonically as a function of the alignment position (ie both
* proteins are sorted).
*
* <p>This will return false for circularly permuted alignments or other non-topological
* alignments. It will also return false for cases where the alignment itself is sequential but it
* is not stored in the afpChain in a sorted manner.
*
* <p>Since algorithms which create non-sequential alignments split the alignment into multiple
* blocks, some computational time can be saved by only checking block boundaries for
* sequentiality. Setting <tt>checkWithinBlocks</tt> to <tt>true</tt> makes this function slower,
* but detects AFPChains with non-sequential blocks.
*
* <p>Note that this method should give the same results as {@link
* AFPChain#isSequentialAlignment()}. However, the AFPChain version relies on the
* StructureAlignment algorithm correctly setting this parameter, which is sadly not always the
* case.
*
* @param afpChain An alignment
* @param checkWithinBlocks Indicates whether individual blocks should be checked for
* sequentiality
* @return True if the alignment is sequential.
*/
public static boolean isSequentialAlignment(AFPChain afpChain, boolean checkWithinBlocks) {
int[][][] optAln = afpChain.getOptAln();
int[] alnLen = afpChain.getOptLen();
int blocks = afpChain.getBlockNum();
if (blocks < 1) return true; // trivial case
if (alnLen[0] < 1) return true;
// Check that blocks are sequential
if (checkWithinBlocks) {
for (int block = 0; block < blocks; block++) {
if (alnLen[block] < 1) continue; // skip empty blocks
int prevRes1 = optAln[block][0][0];
int prevRes2 = optAln[block][1][0];
for (int pos = 1; pos < alnLen[block]; pos++) {
int currRes1 = optAln[block][0][pos];
int currRes2 = optAln[block][1][pos];
if (currRes1 < prevRes1) {
return false;
}
if (currRes2 < prevRes2) {
return false;
}
prevRes1 = currRes1;
prevRes2 = currRes2;
}
}
}
// Check that blocks are sequential
int prevRes1 = optAln[0][0][alnLen[0] - 1];
int prevRes2 = optAln[0][1][alnLen[0] - 1];
for (int block = 1; block < blocks; block++) {
if (alnLen[block] < 1) continue; // skip empty blocks
if (optAln[block][0][0] < prevRes1) {
return false;
}
if (optAln[block][1][0] < prevRes2) {
return false;
}
prevRes1 = optAln[block][0][alnLen[block] - 1];
prevRes2 = optAln[block][1][alnLen[block] - 1];
}
return true;
}
/**
* 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;
}
/**
* Retrieves the optimum alignment from an AFPChain and returns it as a java collection. The
* result is indexed in the same way as {@link AFPChain#getOptAln()}, but has the correct size().
*
* <pre>
* List<List<List<Integer>>> aln = getOptAlnAsList(AFPChain afpChain);
* aln.get(blockNum).get(structureNum={0,1}).get(pos)</pre>
*
* @param afpChain
* @return
*/
public static List<List<List<Integer>>> getOptAlnAsList(AFPChain afpChain) {
int[][][] optAln = afpChain.getOptAln();
int[] optLen = afpChain.getOptLen();
List<List<List<Integer>>> blocks = new ArrayList<List<List<Integer>>>(afpChain.getBlockNum());
for (int blockNum = 0; blockNum < afpChain.getBlockNum(); blockNum++) {
// TODO could improve speed an memory by wrapping the arrays with
// an unmodifiable list, similar to Arrays.asList(...) but with the
// correct size parameter.
List<Integer> align1 = new ArrayList<Integer>(optLen[blockNum]);
List<Integer> align2 = new ArrayList<Integer>(optLen[blockNum]);
for (int pos = 0; pos < optLen[blockNum]; pos++) {
align1.add(optAln[blockNum][0][pos]);
align2.add(optAln[blockNum][1][pos]);
}
List<List<Integer>> block = new ArrayList<List<Integer>>(2);
block.add(align1);
block.add(align2);
blocks.add(block);
}
return blocks;
}
/**
* After the alignment changes (optAln, optLen, blockNum, at a minimum), many other properties
* which depend on the superposition will be invalid.
*
* <p>This method re-runs a rigid superposition over the whole alignment and repopulates the
* required properties, including RMSD (TotalRMSD) and TM-Score.
*
* @param afpChain
* @param ca1
* @param ca2 Second set of ca atoms. Will be modified based on the superposition
* @throws StructureException
* @see {@link CECalculator#calc_rmsd(Atom[], Atom[], int, boolean)} contains much of the same
* code, but stores results in a CECalculator instance rather than an AFPChain
*/
public static void updateSuperposition(AFPChain afpChain, Atom[] ca1, Atom[] ca2)
throws StructureException {
// Update ca information, because the atom array might also be changed
afpChain.setCa1Length(ca1.length);
afpChain.setCa2Length(ca2.length);
// We need this to get the correct superposition
int[] focusRes1 = afpChain.getFocusRes1();
int[] focusRes2 = afpChain.getFocusRes2();
if (focusRes1 == null) {
focusRes1 = new int[afpChain.getCa1Length()];
afpChain.setFocusRes1(focusRes1);
}
if (focusRes2 == null) {
focusRes2 = new int[afpChain.getCa2Length()];
afpChain.setFocusRes2(focusRes2);
}
if (afpChain.getNrEQR() == 0) return;
// create new arrays for the subset of atoms in the alignment.
Atom[] ca1aligned = new Atom[afpChain.getOptLength()];
Atom[] ca2aligned = new Atom[afpChain.getOptLength()];
int pos = 0;
int[] blockLens = afpChain.getOptLen();
int[][][] optAln = afpChain.getOptAln();
assert (afpChain.getBlockNum() <= optAln.length);
for (int block = 0; block < afpChain.getBlockNum(); block++) {
for (int i = 0; i < blockLens[block]; i++) {
int pos1 = optAln[block][0][i];
int pos2 = optAln[block][1][i];
Atom a1 = ca1[pos1];
Atom a2 = (Atom) ca2[pos2].clone();
ca1aligned[pos] = a1;
ca2aligned[pos] = a2;
pos++;
}
}
// this can happen when we load an old XML serialization which did not support modern ChemComp
// representation of modified residues.
if (pos != afpChain.getOptLength()) {
logger.warn(
"AFPChainScorer getTMScore: Problems reconstructing alignment! nr of loaded atoms is "
+ pos
+ " but should be "
+ afpChain.getOptLength());
// we need to resize the array, because we allocated too many atoms earlier on.
ca1aligned = (Atom[]) resizeArray(ca1aligned, pos);
ca2aligned = (Atom[]) resizeArray(ca2aligned, pos);
}
// Superimpose the two structures in correspondance to the new alignment
SVDSuperimposer svd = new SVDSuperimposer(ca1aligned, ca2aligned);
Matrix matrix = svd.getRotation();
Atom shift = svd.getTranslation();
Matrix[] blockMxs = new Matrix[afpChain.getBlockNum()];
Arrays.fill(blockMxs, matrix);
afpChain.setBlockRotationMatrix(blockMxs);
Atom[] blockShifts = new Atom[afpChain.getBlockNum()];
Arrays.fill(blockShifts, shift);
afpChain.setBlockShiftVector(blockShifts);
for (Atom a : ca2aligned) {
Calc.rotate(a, matrix);
Calc.shift(a, shift);
}
// Calculate the RMSD and TM score for the new alignment
double rmsd = SVDSuperimposer.getRMS(ca1aligned, ca2aligned);
double tmScore = SVDSuperimposer.getTMScore(ca1aligned, ca2aligned, ca1.length, ca2.length);
afpChain.setTotalRmsdOpt(rmsd);
afpChain.setTMScore(tmScore);
// Calculate the RMSD and TM score for every block of the new alignment
double[] blockRMSD = new double[afpChain.getBlockNum()];
double[] blockScore = new double[afpChain.getBlockNum()];
for (int k = 0; k < afpChain.getBlockNum(); k++) {
// Create the atom arrays corresponding to the aligned residues in the block
Atom[] ca1block = new Atom[afpChain.getOptLen()[k]];
Atom[] ca2block = new Atom[afpChain.getOptLen()[k]];
int position = 0;
for (int i = 0; i < blockLens[k]; i++) {
int pos1 = optAln[k][0][i];
int pos2 = optAln[k][1][i];
Atom a1 = ca1[pos1];
Atom a2 = (Atom) ca2[pos2].clone();
ca1block[position] = a1;
ca2block[position] = a2;
position++;
}
if (position != afpChain.getOptLen()[k]) {
logger.warn(
"AFPChainScorer getTMScore: Problems reconstructing block alignment! nr of loaded atoms is "
+ pos
+ " but should be "
+ afpChain.getOptLen()[k]);
// we need to resize the array, because we allocated too many atoms earlier on.
ca1block = (Atom[]) resizeArray(ca1block, position);
ca2block = (Atom[]) resizeArray(ca2block, position);
}
// Superimpose the two block structures
SVDSuperimposer svdb = new SVDSuperimposer(ca1block, ca2block);
Matrix matrixb = svdb.getRotation();
Atom shiftb = svdb.getTranslation();
for (Atom a : ca2block) {
Calc.rotate(a, matrixb);
Calc.shift(a, shiftb);
}
// Calculate the RMSD and TM score for the block
double rmsdb = SVDSuperimposer.getRMS(ca1block, ca2block);
double tmScoreb = SVDSuperimposer.getTMScore(ca1block, ca2block, ca1.length, ca2.length);
blockRMSD[k] = rmsdb;
blockScore[k] = tmScoreb;
}
afpChain.setOptRmsd(blockRMSD);
afpChain.setBlockRmsd(blockRMSD);
afpChain.setBlockScore(blockScore);
}
/**
* @param a
* @param ca1
* @param ca2
* @return
* @throws StructureException if an error occurred during superposition
*/
public static AFPChain splitBlocksByTopology(AFPChain a, Atom[] ca1, Atom[] ca2)
throws StructureException {
int[][][] optAln = a.getOptAln();
int blockNum = a.getBlockNum();
int[] optLen = a.getOptLen();
// Determine block lengths
// Split blocks if residue indices don't increase monotonically
List<Integer> newBlkLen = new ArrayList<Integer>();
boolean blockChanged = false;
for (int blk = 0; blk < blockNum; blk++) {
int currLen = 1;
for (int pos = 1; pos < optLen[blk]; pos++) {
if (optAln[blk][0][pos] <= optAln[blk][0][pos - 1]
|| optAln[blk][1][pos] <= optAln[blk][1][pos - 1]) {
// start a new block
newBlkLen.add(currLen);
currLen = 0;
blockChanged = true;
}
currLen++;
}
if (optLen[blk] < 2) {
newBlkLen.add(optLen[blk]);
} else {
newBlkLen.add(currLen);
}
}
// Check if anything needs to be split
if (!blockChanged) {
return a;
}
// Split blocks
List<int[][]> blocks = new ArrayList<int[][]>(newBlkLen.size());
int oldBlk = 0;
int pos = 0;
for (int blkLen : newBlkLen) {
if (blkLen == optLen[oldBlk]) {
assert (pos == 0); // should be the whole block
// Use the old block
blocks.add(optAln[oldBlk]);
} else {
int[][] newBlock = new int[2][blkLen];
assert (pos + blkLen <= optLen[oldBlk]); // don't overrun block
for (int i = 0; i < blkLen; i++) {
newBlock[0][i] = optAln[oldBlk][0][pos + i];
newBlock[1][i] = optAln[oldBlk][1][pos + i];
}
pos += blkLen;
blocks.add(newBlock);
if (pos == optLen[oldBlk]) {
// Finished this oldBlk, start the next
oldBlk++;
pos = 0;
}
}
}
// Store new blocks
int[][][] newOptAln = blocks.toArray(new int[0][][]);
int[] newBlockLens = new int[newBlkLen.size()];
for (int i = 0; i < newBlkLen.size(); i++) {
newBlockLens[i] = newBlkLen.get(i);
}
return replaceOptAln(a, ca1, ca2, blocks.size(), newBlockLens, newOptAln);
}
/**
* Creates a simple interaction format (SIF) file for an alignment.
*
* <p>The SIF file can be read by network software (eg Cytoscape) to analyze alignments as graphs.
*
* <p>This function creates a graph with residues as nodes and two types of edges: 1. backbone
* edges, which connect adjacent residues in the aligned protein 2. alignment edges, which connect
* aligned residues
*
* @param out Stream to write to
* @param afpChain alignment to write
* @param ca1 First protein, used to generate node names
* @param ca2 Second protein, used to generate node names
* @param backboneInteraction Two-letter string used to identify backbone edges
* @param alignmentInteraction Two-letter string used to identify alignment edges
* @throws IOException
*/
public static void alignmentToSIF(
Writer out,
AFPChain afpChain,
Atom[] ca1,
Atom[] ca2,
String backboneInteraction,
String alignmentInteraction)
throws IOException {
// out.write("Res1\tInteraction\tRes2\n");
String name1 = afpChain.getName1();
String name2 = afpChain.getName2();
if (name1 == null) name1 = "";
else name1 += ":";
if (name2 == null) name2 = "";
else name2 += ":";
// Print alignment edges
int nblocks = afpChain.getBlockNum();
int[] blockLen = afpChain.getOptLen();
int[][][] optAlign = afpChain.getOptAln();
for (int b = 0; b < nblocks; b++) {
for (int r = 0; r < blockLen[b]; r++) {
int res1 = optAlign[b][0][r];
int res2 = optAlign[b][1][r];
ResidueNumber rn1 = ca1[res1].getGroup().getResidueNumber();
ResidueNumber rn2 = ca2[res2].getGroup().getResidueNumber();
String node1 = name1 + rn1.getChainId() + rn1.toString();
String node2 = name2 + rn2.getChainId() + rn2.toString();
out.write(String.format("%s\t%s\t%s\n", node1, alignmentInteraction, node2));
}
}
// Print first backbone edges
ResidueNumber rn = ca1[0].getGroup().getResidueNumber();
String last = name1 + rn.getChainId() + rn.toString();
for (int i = 1; i < ca1.length; i++) {
rn = ca1[i].getGroup().getResidueNumber();
String curr = name1 + rn.getChainId() + rn.toString();
out.write(String.format("%s\t%s\t%s\n", last, backboneInteraction, curr));
last = curr;
}
// Print second backbone edges, if the proteins differ
// Do some quick checks for whether the proteins differ
// (Not perfect, but should detect major differences and CPs.)
if (!name1.equals(name2)
|| ca1.length != ca2.length
|| (ca1.length > 0
&& ca1[0].getGroup() != null
&& ca2[0].getGroup() != null
&& !ca1[0]
.getGroup()
.getResidueNumber()
.equals(ca2[0].getGroup().getResidueNumber()))) {
rn = ca2[0].getGroup().getResidueNumber();
last = name2 + rn.getChainId() + rn.toString();
for (int i = 1; i < ca2.length; i++) {
rn = ca2[i].getGroup().getResidueNumber();
String curr = name2 + rn.getChainId() + rn.toString();
out.write(String.format("%s\t%s\t%s\n", last, backboneInteraction, curr));
last = curr;
}
}
}