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PMID:26269173
| Citation |
D'Lima, NG and Teschke, CM (2015) A Molecular Staple: D-Loops in the I Domain of Bacteriophage P22 Coat Protein Make Important Intercapsomer Contacts Required for Procapsid Assembly. J. Virol. 89:10569-79 |
|---|---|
| Abstract |
Bacteriophage P22, a double-stranded DNA (dsDNA) virus, has a nonconserved 124-amino-acid accessory domain inserted into its coat protein, which has the canonical HK97 protein fold. This I domain is involved in virus capsid size determination and stability, as well as protein folding. The nuclear magnetic resonance (NMR) solution structure of the I domain revealed the presence of a D-loop, which was hypothesized to make important intersubunit contacts between coat proteins in adjacent capsomers. Here we show that amino acid substitutions of residues near the tip of the D-loop result in aberrant assembly products, including tubes and broken particles, highlighting the significance of the D-loops in proper procapsid assembly. Using disulfide cross-linking, we showed that the tips of the D-loops are positioned directly across from each other both in the procapsid and the mature virion, suggesting their importance in both states. Our results indicate that D-loop interactions act as "molecular staples" at the icosahedral 2-fold symmetry axis and significantly contribute to stabilizing the P22 capsid for DNA packaging. |
| Links |
PubMed PMC4580156 Online version:10.1128/JVI.01629-15 |
| Keywords |
Bacteriophage P22/chemistry; Bacteriophage P22/genetics; Bacteriophage P22/metabolism; Capsid/chemistry; Capsid/metabolism; Capsid Proteins/chemistry; Capsid Proteins/genetics; Capsid Proteins/metabolism; Cross-Linking Reagents/chemistry; DNA/chemistry; DNA/metabolism; DNA Packaging/physiology; DNA, Viral/chemistry; DNA, Viral/metabolism; Gene Expression; Models, Molecular; Phenanthrolines/chemistry; Protein Folding; Protein Structure, Secondary; Protein Structure, Tertiary; Salmonella typhimurium/virology; Virion/chemistry; Virion/genetics; Virion/metabolism; Virus Assembly/physiology |
Significance
Annotations
| Gene product | Qualifier | GO Term | Evidence Code | with/from | Aspect | Extension | Notes | Status |
|---|---|---|---|---|---|---|---|---|
| GO:0046797: viral procapsid maturation |
ECO:0000315: |
P |
Mutant phenotypes D244A and D246A were used to show the role of the D-loop in procapsid maturation. In figure 2A, the wild type shows 2 peaks corresponding to procapsid protein around fraction 16 and mature phages that incorporated the coat protein at fraction 23. D244A mutant showed improperly formed procapsids in figure 2B which could correspond to the protein peak at fraction 16 in figure 2A. D244A showed very little coat protein at fraction 23 indicating phages were not produced. The D246A mutants showed no significant amount of procapsid protein at fraction 16. In figure 2B the D246A mutant showed particles that were incomplete instead of procapsid proteins that were present in wild types. This mutant also showed no peak of mature coat protein at fraction 23 indicating the phages were not able to form. |
complete | ||||
| GO:0046729: viral procapsid |
ECO:0000314: |
C |
Figure 7. By testing disulfold crosslink form or not among purified proteins N245/C405S and L243C/C405 under room temperature and high temperature, they conclude that tips of the D-loop locates in close proximity at the 2-fold axis between coat sub-units both in capsid and precapsid. And the tips would remain in proximity after capsid expansion. |
complete | ||||
Notes
See also
References
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