Mechanistic Insights into Water–Protein Interactions of Filamentous Bacteriophage

• Published in: The journal of physical chemistry. B 2013-03, Vol.117 (10), p.2837-2840
• Main Authors: Purusottam, Rudra N, Rai, Ratan K, Sinha, Neeraj
• Format: Article
• Language: English
• Subjects: Assembly; Bacteria; Bacteriophage Pf1 - chemistry; Bacteriophage Pf1 - metabolism; Capsid Proteins - chemistry; Capsid Proteins - metabolism; Correlation; Magnetic resonance; Models, Molecular; Nuclear magnetic resonance; Nuclear Magnetic Resonance, Biomolecular; Polyethylene glycol; Proteins; Spinning; Two dimensional; Water - chemistry; Water - metabolism
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp310921n

Water plays a major structural and functional role around proteins. In an attempt to explore this mechanistic structural aspect of proteins, we present site-specific interaction of hydration water with the major coat protein subunit of filamentous virus Pf1 by magic angle spinning (MAS) solid-state NMR. The interaction of surrounding water with 36 MDa Pf1 virion is investigated in uniformly 13C, 15N isotopically labeled; polyethylene glycol precipitated fully hydrated samples by solid-state nuclear magnetic resonance spectroscopy. Dipolar edited two-dimensional (2D) 1H–15N heteronuclear correlation (HETCOR) experiments lead to unambiguous assignments of cross-peaks originating exclusively from 1H resonances of water molecules correlating to the protein amide nitrogen. An enhanced resolved 1H chemical shift dimension in these experiments also precludes the need of perdeuteration. We report seven residues spanning the 40-residue continuous α-helical conformation assembly of Pf1 interacting with surrounding water. It shows a highly hydrated inner core inside this viral filamentous assembly. The results obtained also suggest the first evidence of a water-mediated interface cluster formed at the site of Arg44 with the single-stranded DNA genome of the filamentous phage supramolecular assembly.