Functional characterization of Helicobacter pylori DnaB helicase.
Helicobacter pylori causes gastric ulcer diseases and gastric adenocarcinoma in humans. Not much is known regarding DNA replication in H.pylori that is important for cell survival. Here we report the cloning, expression and characterization of H.pylori DnaB (HpDnaB) helicase both in vitro and in vivo. Among the DnaB homologs, only Escherichia coli DnaB has been studied extensively. HpDnaB showed strong 5' to 3' helicase and ATPase activity. Interestingly, H.pylori does not have an obvious DnaC homolog which is essential for DnaB loading on the E.coli chromosomal DNA replication origin (oriC). However, HpDnaB can functionally complement the E.coli DnaB temperature-sensitive mutant at the non-permissive temperature, confirming that HpDnaB is a true replicative helicase. Escherichia coli DnaC co-eluted in the same fraction with HpDnaB following gel filtration analysis suggesting that these proteins might physically interact with each other. It is possible that a functional DnaC homolog is present in H.pylori. The complete characterization of H.pylori DnaB helicase will also help the comparative analysis of DnaB helicases among bacteria.
Soni
Rajesh K
RK
Special Centre For Molecular Medicine, Jawaharlal Nehru University, New Delhi 110067, India.
Mehra
Parul
P
Choudhury
Nirupam Roy
NR
Mukhopadhyay
Gauranga
G
Dhar
Suman Kumar
SK
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D002118:Calcium / Q000494:pharmacology; D002413:Cations, Divalent / Q000494:pharmacology; D003001:Cloning, Molecular; D004265:DNA Helicases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D053488:DnaB Helicases; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005816:Genetic Complementation Test; D016480:Helicobacter pylori / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D009711:Nucleotides / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D013696:Temperature; D014544:Uridine Triphosphate / Q000378:metabolism
D001426:Bacterial Proteins; D002413:Cations, Divalent; D009711:Nucleotides; D011189:Potassium Chloride; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D004265:DNA Helicases; D053488:DnaB Helicases; D002118:Calcium; D014544:Uridine Triphosphate