Structure of Escherichia coli dnaC. Identification of a cysteine residue possibly involved in association with dnaB protein.
The nucleotide sequence of the Escherichia coli dnaC gene and the primary structure of the dnaC protein were determined. The NH2-terminal amino acid sequence of the dnaC protein matched that predicted from the nucleotide sequence of the 735-base pair coding region. The dnaC gene lacks characteristic promoter structures; neither the "Pribnow box" nor the "-35 sequence" was detected within 222 base pairs upstream from the initiator ATG codon. There is, however, a typical Shine-Dalgarno sequence 7-10 base pairs before the ATG codon. An upstream open reading frame, separated by just 2 base pairs from the coding region of dnaC, encodes the COOH-terminal half of the dnaT product (protein i; Masai, H., Bond, M. W., and Arai, K. (1986) Proc. Natl. Acad. Sci. U. S. A. 83, 1256-1260). The dnaC protein contains 245 amino acids with a calculated molecular weight of 27,894 consistent with the observed value (29,000). Similar to dnaG and dnaT, dnaC uses several minor codons; the significance of these minor codons to the low level expression of the protein product in E. coli cells remains to be determined. The in vitro site-directed mutagenesis method was employed to determine the functional region involved in interaction with dnaB protein. The first cysteine residue located in the NH2-terminal region of the dnaC protein (Cys69) was shown to be important for this activity. Overall sequence homology between dnaC protein and lambda P protein, functionally analogous to the dnaC protein in the lambda phage DNA replication, is not extensive. There are, however, several short stretches of homologous regions including the NH2-terminal eight amino acids and the Cys78 region of dnaC protein.
Nakayama
N
N
Bond
M W
MW
Miyajima
A
A
Kobori
J
J
Arai
K
K
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D003062:Codon; D003545:Cysteine; D004265:DNA Helicases; D004269:DNA, Bacterial / Q000235:genetics; D053488:DnaB Helicases; D004926:Escherichia coli / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010446:Peptide Fragments; D012689:Sequence Homology, Nucleic Acid
D001426:Bacterial Proteins; D003062:Codon; D004269:DNA, Bacterial; D010446:Peptide Fragments; D004265:DNA Helicases; D053488:DnaB Helicases; D003545:Cysteine