title: Hydration of protein-protein interfaces.
abstract: We present an analysis of the water molecules immobilized at the protein-protein interfaces of 115 homodimeric proteins and 46 protein-protein complexes, and compare them with 173 large crystal packing interfaces representing nonspecific interactions. With an average of 15 waters per 1000 A2 of interface area, the crystal packing interfaces are more hydrated than the specific interfaces of homodimers and complexes, which have 10-11 waters per 1000 A2, reflecting the more hydrophilic composition of crystal packing interfaces. Very different patterns of hydration are observed: Water molecules may form a ring around interfaces that remain "dry," or they may permeate "wet" interfaces. A majority of the specific interfaces are dry and most of the crystal packing interfaces are wet, but counterexamples exist in both categories. Water molecules at interfaces form hydrogen bonds with protein groups, with a preference for the main-chain carbonyl and the charged side-chains of Glu, Asp, and Arg. These interactions are essentially the same in specific and nonspecific interfaces, and very similar to those observed elsewhere on the protein surface. Water-mediated polar interactions are as abundant at the interfaces as direct protein-protein hydrogen bonds, and they may contribute to the stability of the assembly.
authors.affiliation: Laboratoire d'Enzymologie et de Biochimie Structurales, Gif-sur-Yvette, France.
authors.forename: Francis
authors.initials: F
authors.lastname: Rodier
authors.forename: Ranjit Prasad
authors.initials: RP
authors.lastname: Bahadur
authors.forename: Pinak
authors.initials: P
authors.lastname: Chakrabarti
authors.forename: Joël
authors.initials: J
authors.lastname: Janin
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D018360:Crystallography, X-Ray; D030562:Databases, Protein; D019281:Dimerization; D006860:Hydrogen Bonding; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D011506:Proteins; D014867:Water