3aa3
A52L E. coli RNase HIA52L E. coli RNase HI
Structural highlights
Function[RNH_ECOLI] Endonuclease that specifically degrades the RNA of RNA-DNA hybrids. RNase H participates in DNA replication; it helps to specify the origin of genomic replication by suppressing initiation at origins other than the oriC locus; along with the 5'-3' exonuclease of pol1, it removes RNA primers from the Okazaki fragments of lagging strand synthesis; and it defines the origin of replication for ColE1-type plasmids by specific cleavage of an RNA preprimer.[HAMAP-Rule:MF_00042] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedIt has generally been accepted that an increase in protein stability is proportional to the increase in hydrophobicity. When a cavity is created by large-to-small substitutions of amino acid residues in protein cores, protein stability decreases 5.3 kJ/mol per single methyl(ene) group removal. In contrast, many reported cavity-filling mutations either failed to increase stability or produced marginal increases in stability; even in successful cases, the increase in stability was much lower than expected from the cost of single methyl(ene) group removal in cavity-creating mutations. Previously it was found that some cavity-filling mutant proteins at Ala52 in E. coli RNase HI increased stability, but decreased activity and they did not increase the stability to the degree expected by the hydrophobic effect alone. The present study attempted to structurally analyze these variant proteins, and it was found that substitutions have little effect on the overall fold but cause conformational strains with the neighboring residues. The present results and literature on cavity-creating/-filling variants provide insight into protein architecture, indicating that natural protein cores are able to accommodate larger side-chain residue by substitution; in other words, excess-packing may not be chosen in natural selection. Protein core adaptability: crystal structures of the cavity-filling variants of Escherichia coli RNase HI.,Tanaka M, Chon H, Angkawidjaja C, Koga Y, Takano K, Kanaya S Protein Pept Lett. 2010 Sep;17(9):1163-9. PMID:20423323[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences |
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