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Two domains of superfamily I helicases may exist as separate proteins.

ABSTRACT: DNA and RNA helicases of superfamily I are characterized by seven conserved motifs. The five N-terminal motifs are separated from the two C-terminal ones by a spacer that is highly variable in both sequence and length, suggesting the existence of two distinct domains. Using computer methods for protein sequence analysis, we show that PhoH, an ATP-binding protein that is conserved in Escherichia coli and Mycobacterium leprae, is homologous to the putative N-terminal domain of the helicases, whereas the putative E. coli protein YjhR is homologous to the C-terminal domain. These findings suggest that the N-and C-terminal domains of superfamily I helicases have distinct activities, with only the N-terminal domain having the ATPase activity. It is speculated that PhoH and YjhR have evolved from helicases through deletion of the portions of the helicase genes coding for the C- and N-terminal domain, respectively.

SUBMITTER: Koonin EV

PROVIDER: S-EPMC2143243 | biostudies-other | 1996 Jan

REPOSITORIES: biostudies-other

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Two domains of superfamily I helicases may exist as separate proteins.

Koonin E V EV Rudd K E KE

Protein science : a publication of the Protein Society 19960101 1

DNA and RNA helicases of superfamily I are characterized by seven conserved motifs. The five N-terminal motifs are separated from the two C-terminal ones by a spacer that is highly variable in both sequence and length, suggesting the existence of two distinct domains. Using computer methods for protein sequence analysis, we show that PhoH, an ATP-binding protein that is conserved in Escherichia coli and Mycobacterium leprae, is homologous to the putative N-terminal domain of the helicases, where ...[more]

PMID: 8771213

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