Detection and analysis of chromosomal arsenic resistance in Pseudomonas fluorescens strain MSP3.
Pseudomonas fluorescens MSP3 isolated from sea water was resistant to arsenate. This bacterium harbored no plasmids, indicating that arsenic resistance was chromosomally encoded. The chromosomal DNA from MSP3 when transformed onto Escherichia coli DH5alpha using pBluescript exhibited resistance to sodium arsenate and sodium arsenite. Three clones MSA1, MSA2, and MSI3 containing the ars genes were obtained and further subcloning resulted in three fragments of size 2.2, 2.6, and 2.1 kb for pMSA11, pMSA12, and pMSI13, respectively, which contained the genes arsRBC of the arsenic operon. An efflux mechanism of detoxification was observed which was ATP dependent. The resistance mechanism was encoded from a single operon which consisted of an arsenite inducible repressor that regulates the expression of arsenate reductase (ars C) and inner membrane associated arsenite export system encoded by ars B. The chromosomal operon was cloned, sequenced, and found to consist of three cistrons, named as ars R, ars B, and ars C. Southern hybridization and mating experiments confirmed the functioning of the ars genes in the operon, thereby conferring increased resistance to sodium arsenate and sodium arsenite.
Prithivirajsingh
S
S
Department of Experimental Radiation Oncology, University of Texas-MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030, USA. pssing@mail.mdanderson.org
Mishra
S K
SK
Mahadevan
A
A
D000251:Adenosine Triphosphatases / Q000235:genetics; D000595:Amino Acid Sequence; D001149:Arsenates / Q000378:metabolism / Q000494:pharmacology; D001151:Arsenic / Q000378:metabolism / Q000494:pharmacology*; D053501:Arsenite Transporting ATPases; D018053:Arsenites / Q000378:metabolism / Q000494:pharmacology; D001426:Bacterial Proteins; D001483:Base Sequence; D002876:Chromosomes, Bacterial / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D004274:DNA, Recombinant; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D016623:Ion Pumps; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes; D009154:Mutation; D009876:Operon / Q000235:genetics*; D010957:Plasmids / Q000235:genetics; D011551:Pseudomonas fluorescens / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013723:Teratogens / Q000378:metabolism / Q000494:pharmacology; D015534:Trans-Activators / Q000235:genetics
C489527:ArsR protein, E coli; D001149:Arsenates; D018053:Arsenites; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004274:DNA, Recombinant; D029968:Escherichia coli Proteins; D016623:Ion Pumps; D009097:Multienzyme Complexes; D013723:Teratogens; D015534:Trans-Activators; D000251:Adenosine Triphosphatases; D053501:Arsenite Transporting ATPases; D001151:Arsenic; C025657:arsenic acid