Functional analysis of iceA1, a CATG-recognizing restriction endonuclease gene in Helicobacter pylori.
iceA1 in Helicobacter pylori is a homolog of nlaIIIR, which encodes the CATG-specific restriction endonuclease NlaIII in Neisseria lactamica. Analysis of iceA1 sequences from 49 H.pylori strains shows that a full-length NlaIII-like ORF is present in 10 strains, including CH4, but in other strains, including strain 60190, the ORFs are truncated due to a variety of mutations. Our goal was to determine whether iceA1 can encode a NlaIII-like endonuclease. Overexpression in Escherichia coli of iceA1 from CH4, but not from 60190, yielded NlaIII-like activity, indicating that the full-length iceA1 is a functional endonuclease gene. Repair of the iceA1 frameshift mutation in strain 60190 and its expression in E.coli yielded functional NlaIII-like activity. We conclude that iceA1 in CH4 is a functional restriction endonuclease gene, while iceA1 in 60190 is not, due to a frameshift mutation, but that its repair restores its restriction endonuclease activity.
Xu
Qing
Q
Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
Morgan
R D
RD
Roberts
R J
RJ
Xu
S Y
SY
van Doorn
L J
LJ
Donahue
J P
JP
Miller
G G
GG
Blaser
Martin J
MJ
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D004262:DNA Restriction Enzymes / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D015252:Deoxyribonucleases, Type II Site-Specific / Q000235:genetics / Q000378:metabolism; D004925:Escherichia / Q000235:genetics; D016368:Frameshift Mutation / Q000235:genetics; D016480:Helicobacter pylori / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D009343:Neisseria / Q000201:enzymology; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D011994:Recombinant Proteins; C405087:iceA1 protein, Helicobacter pylori; D004262:DNA Restriction Enzymes; C048422:endodeoxyribonuclease NlaIII; D015252:Deoxyribonucleases, Type II Site-Specific