Molecular modeling study on the effect of residues distant from the nucleotide-binding portion on RNA binding in Staphylococcus aureus Hfq.
Hfq is an abundant RNA-binding bacterial protein that was first identified in E. coli as a required host factor for phage Qbeta RNA replication. The pleiotrophic phenotype resulting from the deletion of Hfq predicates the importance of this protein. Two RNA-binding sites have been characterized: the proximal site which binds sRNA and mRNA and the distal site which binds poly(A) tails. Previous studies mainly focused on the key residues in the proximal site of the protein. A recent mutation study in E. coli Hfq showed that a distal residue Val43 is important for the protein function. Interestingly, when we analyzed the sequence and structure of Staphylococcus aureus Hfq using the CONSEQ server, the results elicited that more functional residues were located far from the nucleotide-binding portion (NBP). From the analysis seven individual residues Asp9, Leu12, Glu13, Lys16, Gln31, Gly34 and Asp40 were selected to investigate the conformational changes in Hfq-RNA complex due to point mutation effect of those residues using molecular dynamics simulations. Results showed a significant effect on Asn28 which is an already known highly conserved functionally important residue. Mutants D9A, E13A and K16A depicted effects on base stacking along with increase in RNA pore diameter, which is required for the threading of RNA through the pore for the post-translational modification. Further, the result of protein stability analysis by the CUPSAT server showed destabilizing effect in the most mutants. From this study we characterized a series of important residues located far from the NBP and provide some clues that those residues may affect sRNA binding in Hfq.
Lazar
Prettina
P
Division of Applied Life Science (BK21 Program), Environmental Biotechnology National Core Research Center (EB-NCRC), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Gyeongsang National University (GNU), Jinju 660-701, Republic of Korea.
Kim
Songmi
S
Lee
Yuno
Y
Son
Minky
M
Kim
Hyong-Ha
HH
Kim
Yong Seong
YS
Lee
Keun Woo
KW
D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D035001:Host Factor 1 Protein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D056004:Molecular Dynamics Simulation; D017354:Point Mutation; D011485:Protein Binding; D012329:RNA, Bacterial / Q000737:chemistry / Q000378:metabolism*; D013211:Staphylococcus aureus / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D035001:Host Factor 1 Protein; D012329:RNA, Bacterial