Suppression of Escherichia coli alkB mutants by Saccharomyces cerevisiae genes.
The alkB gene is one of a group of alkylation-inducible genes in Escherichia coli, and its product protects cells from SN2-type alkylating agents such as methyl methanesulfonate (MMS). However, the precise biochemical function of the AlkB protein remains unknown. Here, we describe the cloning, sequencing, and characterization of three Saccharomyces cerevisiae genes (YFW1, YFW12, and YFW16) that functionally complement E. coli alkB mutant cells. DNA sequence analysis showed that none of the three gene products have any amino acid sequence homology with the AlkB protein. The YFW1 and YFW12 proteins are highly serine and threonine rich, and YFW1 contains a stretch of 28 hydrophobic residues, indicating that it may be a membrane protein. The YFW16 gene turned out to be allelic with the S. cerevisiae STE11 gene. STE11 is a protein kinase known to be involved in pheromone signal transduction in S. cerevisiae; however, the kinase activity is not required for MMS resistance because mutant STE11 proteins lacking kinase activity could still complement E. coli alkB mutants. Despite the fact that YFW1, YFW12, and YFW16/STE11 each confer substantial MMS resistance upon E. coli alkB cells, S. cerevisiae null mutants for each gene were not MMS sensitive. Whether these three genes provide alkylation resistance in E. coli via an alkB-like mechanism remains to be determined, but protection appears to be specific for AlkB-deficient E. coli because none of the genes protect other alkylation-sensitive E. coli strains from killing by MMS.
Wei
Y F
YF
Department of Molecular and Cellular Toxicology, Harvard School of Public Health, Boston, Massachusetts, USA.
Chen
B J
BJ
Samson
L
L
D000478:Alkylation; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D042926:Cytochrome P-450 CYP4A; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D004249:DNA Damage / Q000235:genetics*; D004252:DNA Mutational Analysis; D018076:DNA, Complementary / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D029968:Escherichia coli Proteins; D005656:Fungal Proteins / Q000235:genetics; D005800:Genes, Fungal / Q000235:genetics*; D005816:Genetic Complementation Test; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D006899:Mixed Function Oxygenases / Q000235:genetics*; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D013489:Suppression, Genetic; D014157:Transcription Factors
D001426:Bacterial Proteins; D018076:DNA, Complementary; D029968:Escherichia coli Proteins; D005656:Fungal Proteins; D008565:Membrane Proteins; C095462:PRY2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D014157:Transcription Factors; C095461:WSC4 protein, S cerevisiae; C071596:ste11 protein, S pombe; D003577:Cytochrome P-450 Enzyme System; D008741:Methyl Methanesulfonate; D006899:Mixed Function Oxygenases; C466427:AlkB protein, E coli; D042926:Cytochrome P-450 CYP4A; D020930:MAP Kinase Kinase Kinases; C067018:Ste11 protein, S cerevisiae