Add 3di encoding to biotite.structure

doc/apidoc.json

@@ -376,7 +376,6 @@
             "set_component",
             "list_assemblies",
             "get_assembly"
-
         ],
         "CIF format" : [
             "CIFFile",
@@ -402,5 +401,13 @@
             "StringArrayEncoding",
             "TypeCode"
         ]
+    },
+    "biotite.structure.alphabet" : {
+        "Structural alphabets": [
+            "I3DSequence"
+        ],
+        "Conversion Function": [
+            "to_3di"
+        ]
     }
 }

doc/references.bib

@@ -742,7 +742,7 @@ @article{Steele2021
   eprint = {2001.05304},
   primaryclass = {cs},
   doi = {10.48550/arXiv.2001.05304},
-  archiveprefix = {arxiv}
+  archiveprefix = {arXiv}
 }
 
 @article{Steinegger2017,
@@ -838,6 +838,20 @@ @article{VanHerk1992
   doi = {10.1016/0167-8655(92)90069-C}
 }
 
+@article{VanKempen2024,
+  title = {Fast and Accurate Protein Structure Search with {{Foldseek}}},
+  author = {{van Kempen}, Michel and Kim, Stephanie S. and Tumescheit, Charlotte and Mirdita, Milot and Lee, Jeongjae and Gilchrist, Cameron L. M. and Söding, Johannes and Steinegger, Martin},
+  year = {2024},
+  month = feb,
+  journal = {Nature Biotechnology},
+  volume = {42},
+  number = {2},
+  pages = {243--246},
+  publisher = {Nature Publishing Group},
+  issn = {1546-1696},
+  doi = {10.1038/s41587-023-01773-0}
+}
+
 @article{Westbrook2015,
   title = {The Chemical Component Dictionary: Complete Descriptions of Constituent Molecules in Experimentally Determined {{3D}} Macromolecules in the {{Protein Data Bank}}},
   shorttitle = {The Chemical Component Dictionary},

src/biotite/sequence/align/matrix.py

@@ -2,14 +2,17 @@
 # under the 3-Clause BSD License. Please see 'LICENSE.rst' for further
 # information.
 
+__all__ = ["SubstitutionMatrix"]
 __name__ = "biotite.sequence.align"
 __author__ = "Patrick Kunzmann"
 
-import os
+import functools
+from pathlib import Path
 import numpy as np
 from biotite.sequence.seqtypes import NucleotideSequence, ProteinSequence
 
-__all__ = ["SubstitutionMatrix"]
+# Directory of matrix files
+_DB_DIR = Path(__file__).parent / "matrix_data"
 
 
 class SubstitutionMatrix(object):
@@ -59,6 +62,10 @@ class SubstitutionMatrix(object):
             - **RBLOSUM<n>_<BLOCKS>**
             - **CorBLOSUM<n>_<BLOCKS>**
 
+        - Structural alphabet substitution matrices
+
+            - **3Di** - For 3Di alphabet from ``foldseek`` :footcite:`VanKempen2024`
+
     A list of all available matrix names is returned by
     :meth:`list_db()`.
 
@@ -124,9 +131,6 @@ class SubstitutionMatrix(object):
     >>> matrix = SubstitutionMatrix(alph, alph, "BLOSUM50")
     """
 
-    # Directory of matrix files
-    _db_dir = os.path.join(os.path.dirname(os.path.realpath(__file__)), "matrix_data")
-
     def __init__(self, alphabet1, alphabet2, score_matrix):
         self._alph1 = alphabet1
         self._alph2 = alphabet2
@@ -350,7 +354,7 @@ def dict_from_db(matrix_name):
         matrix_dict : dict
             A dictionary representing the substitution matrix.
         """
-        filename = SubstitutionMatrix._db_dir + os.sep + matrix_name + ".mat"
+        filename = _DB_DIR / f"{matrix_name}.mat"
         with open(filename, "r") as f:
             return SubstitutionMatrix.dict_from_str(f.read())
 
@@ -364,11 +368,10 @@ def list_db():
         db_list : list
             List of matrix names in the internal database.
         """
-        files = os.listdir(SubstitutionMatrix._db_dir)
-        # Remove '.mat' from files
-        return [file[:-4] for file in sorted(files)]
+        return [path.stem for path in _DB_DIR.glob("*.mat")]
 
     @staticmethod
+    @functools.cache
     def std_protein_matrix():
         """
         Get the default :class:`SubstitutionMatrix` for protein sequence
@@ -379,9 +382,12 @@ def std_protein_matrix():
         matrix : SubstitutionMatrix
             Default matrix.
         """
-        return _matrix_blosum62
+        return SubstitutionMatrix(
+            ProteinSequence.alphabet, ProteinSequence.alphabet, "BLOSUM62"
+        )
 
     @staticmethod
+    @functools.cache
     def std_nucleotide_matrix():
         """
         Get the default :class:`SubstitutionMatrix` for DNA sequence
@@ -392,13 +398,23 @@ def std_nucleotide_matrix():
         matrix : SubstitutionMatrix
             Default matrix.
         """
-        return _matrix_nuc
+        return SubstitutionMatrix(
+            NucleotideSequence.alphabet_amb, NucleotideSequence.alphabet_amb, "NUC"
+        )
+
+    @staticmethod
+    @functools.cache
+    def std_3di_matrix():
+        """
+        Get the default :class:`SubstitutionMatrix` for 3Di sequence
+        alignments.
 
+        Returns
+        -------
+        matrix : SubstitutionMatrix
+            Default matrix.
+        """
+        # Import inside function to avoid circular import
+        from biotite.structure.alphabet.i3d import I3DSequence
 
-# Preformatted BLOSUM62 and NUC substitution matrix from NCBI
-_matrix_blosum62 = SubstitutionMatrix(
-    ProteinSequence.alphabet, ProteinSequence.alphabet, "BLOSUM62"
-)
-_matrix_nuc = SubstitutionMatrix(
-    NucleotideSequence.alphabet_amb, NucleotideSequence.alphabet_amb, "NUC"
-)
+        return SubstitutionMatrix(I3DSequence.alphabet, I3DSequence.alphabet, "3Di")

src/biotite/sequence/align/matrix_data/3Di.mat

@@ -0,0 +1,25 @@
+# 3Di bit/2
+# Background (precomputed optional): 0.0489372 0.0306991 0.101049 0.0329671 0.0276149 0.0416262 0.0452521 0.030876 0.0297251 0.0607036 0.0150238 0.0215826 0.0783843 0.0512926 0.0264886 0.0610702 0.0201311 0.215998 0.0310265 0.0295417 0.00001
+# Lambda     (precomputed optional): 0.351568
+    A   C   D   E   F   G   H   I   K   L   M   N   P   Q   R   S   T   V   W   Y   X
+A   6  -3   1   2   3  -2  -2  -7  -3  -3 -10  -5  -1   1  -4  -7  -5  -6   0  -2   0
+C  -3   6  -2  -8  -5  -4  -4 -12 -13   1 -14   0   0   1  -1   0  -8   1  -7  -9   0
+D   1  -2   4  -3   0   1   1  -3  -5  -4  -5  -2   1  -1  -1  -4  -2  -3  -2  -2   0
+E   2  -8  -3   9  -2  -7  -4 -12 -10  -7 -17  -8  -6  -3  -8 -10 -10 -13  -6  -3   0
+F   3  -5   0  -2   7  -3  -3  -5   1  -3  -9  -5  -2   2  -5  -8  -3  -7   4  -4   0
+G  -2  -4   1  -7  -3   6   3   0  -7  -7  -1  -2  -2  -4   3  -3   4  -6  -4  -2   0
+H  -2  -4   1  -4  -3   3   6  -4  -7  -6  -6   0  -1  -3   1  -3  -1  -5  -5   3   0
+I  -7 -12  -3 -12  -5   0  -4   8  -5 -11   7  -7  -6  -6  -3  -9   6 -12  -5  -8   0
+K  -3 -13  -5 -10   1  -7  -7  -5   9 -11  -8 -12  -6  -5  -9 -14  -5 -15   5  -8   0
+L  -3   1  -4  -7  -3  -7  -6 -11 -11   6 -16  -3  -2   2  -4  -4  -9   0  -8  -9   0
+M -10 -14  -5 -17  -9  -1  -6   7  -8 -16  10  -9  -9 -10  -5 -10   3 -16  -6  -9   0
+N  -5   0  -2  -8  -5  -2   0  -7 -12  -3  -9   7   0  -2   2   3  -4   0  -8  -5   0
+P  -1   0   1  -6  -2  -2  -1  -6  -6  -2  -9   0   4   0   0  -2  -4   0  -4  -5   0
+Q   1   1  -1  -3   2  -4  -3  -6  -5   2 -10  -2   0   5  -2  -4  -5  -1  -2  -5   0
+R  -4  -1  -1  -8  -5   3   1  -3  -9  -4  -5   2   0  -2   6   2   0  -1  -6  -3   0
+S  -7   0  -4 -10  -8  -3  -3  -9 -14  -4 -10   3  -2  -4   2   6  -6   0 -11  -9   0
+T  -5  -8  -2 -10  -3   4  -1   6  -5  -9   3  -4  -4  -5   0  -6   8  -9  -5  -5   0
+V  -6   1  -3 -13  -7  -6  -5 -12 -15   0 -16   0   0  -1  -1   0  -9   3 -10 -11   0
+W   0  -7  -2  -6   4  -4  -5  -5   5  -8  -6  -8  -4  -2  -6 -11  -5 -10   8  -6   0
+Y  -2  -9  -2  -3  -4  -2   3  -8  -8  -9  -9  -5  -5  -5  -3  -9  -5 -11  -6   9   0
+X   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0

src/biotite/structure/alphabet/__init__.py

@@ -0,0 +1,12 @@
+# This source code is part of the Biotite package and is distributed
+# under the 3-Clause BSD License. Please see 'LICENSE.rst' for further
+# information.
+
+"""
+A subpackage for converting structures to structural alphabet sequences.
+"""
+
+__name__ = "biotite.structure.alphabet"
+__author__ = "Martin Larralde, Patrick Kunzmann"
+
+from .i3d import *