Constitutive arsenite oxidase expression detected in arsenic-hypertolerant Pseudomonas xanthomarina S11

ABSTRACT The chemolithoautotroph NT-26 oxidizes arsenite to arsenate by using a periplasmic arsenite oxidase. Purification and preliminary characterization of the enzyme revealed that it (i) contains two heterologous subunits, AroA (98 kDa) and AroB (14 kDa); (ii) has a native molecular mass of 219 kDa, suggesting an α2β2 configuration; and (iii) contains two molybdenum and 9 or 10 iron atoms per α2β2 unit. The genes that encode the enzyme have been cloned and sequenced. Sequence analyses revealed similarities to the arsenite oxidase of Alcaligenes faecalis, the putative arsenite oxidase of the beta-proteobacterium ULPAs1, and putative proteins of Aeropyrum pernix, Sulfolobus tokodaii, and Chloroflexus aurantiacus. Interestingly, the AroA subunit was found to be similar to the molybdenum-containing subunits of enzymes in the dimethyl sulfoxide reductase family, whereas the AroB subunit was found to be similar to the Rieske iron-sulfur proteins of cytochrome bc 1 and b 6 f complexes. The NT-26 arsenite oxidase is probably exported to the periplasm via the Tat secretory pathway, with the AroB leader sequence used for export. Confirmation that NT-26 obtains energy from the oxidation of arsenite was obtained, as an aroA mutant was unable to grow chemolithoautotrophically with arsenite. This mutant could grow heterotrophically in the presence of arsenite; however, the arsenite was not oxidized to arsenate.

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Heterologously expressed arsenite oxidase: A system to study biogenesis and structure/function relationships of the enzyme family

Biochimica et Biophysica Acta (BBA) - Bioenergetics ◽

10.1016/j.bbabio.2012.06.001 ◽

2012 ◽

Vol 1817 (9) ◽

pp. 1701-1708 ◽

Cited By ~ 11

Author(s):

Robert van Lis ◽

Wolfgang Nitschke ◽

Thomas P. Warelow ◽

Line Capowiez ◽

Joanne M. Santini ◽

...

Keyword(s):

Structure Function ◽

Arsenite Oxidase ◽

Enzyme Family

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The Small Subunit AroB of Arsenite Oxidase

Journal of Biological Chemistry ◽

10.1074/jbc.m110.113811 ◽

2010 ◽

Vol 285 (27) ◽

pp. 20442-20451 ◽

Cited By ~ 28

Author(s):

Simon Duval ◽

Joanne M. Santini ◽

Wolfgang Nitschke ◽

Russ Hille ◽

Barbara Schoepp-Cothenet

Keyword(s):

Small Subunit ◽

Arsenite Oxidase

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Effect of arsenite on swimming motility delays surface colonization in Herminiimonas arsenicoxydans

Microbiology ◽

10.1099/mic.0.039313-0 ◽

2010 ◽

Vol 156 (8) ◽

pp. 2336-2342 ◽

Cited By ~ 21

Author(s):

M. Marchal ◽

R. Briandet ◽

S. Koechler ◽

B. Kammerer ◽

P. N. Bertin

Keyword(s):

Laser Scanning ◽

Time Course ◽

Wild Type Strain ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Wild Type ◽

Arsenite Oxidase ◽

Swimming Motility ◽

In The Wild ◽

Biofilm Development

Herminiimonas arsenicoxydans is a Gram-negative bacterium able to detoxify arsenic-contaminated environments by oxidizing arsenite [As(III)] to arsenate [As(V)] and by scavenging arsenic ions in an extracellular matrix. Its motility and colonization behaviour have been previously suggested to be influenced by arsenite. Using time-course confocal laser scanning microscopy, we investigated its biofilm development in the absence and presence of arsenite. Arsenite was shown to delay biofilm initiation in the wild-type strain; this was partly explained by its toxicity, which caused an increased growth lag time. However, this delayed adhesion step in the presence of arsenite was not observed in either a swimming motility defective fliL mutant or an arsenite oxidase defective aoxB mutant; both strains displayed the wild-type surface properties and growth capacities. We propose that during the biofilm formation process arsenite acts on swimming motility as a result of the arsenite oxidase activity, preventing the switch between planktonic and sessile lifestyles. Our study therefore highlights the existence, under arsenite exposure, of a competition between swimming motility, resulting from arsenite oxidation, and biofilm initiation.

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Cold-adapted arsenite oxidase from a psychrotolerant Polaromonas species

Metallomics ◽

10.1039/c2mt20180a ◽

2013 ◽

Vol 5 (4) ◽

pp. 318-324 ◽

Cited By ~ 6

Author(s):

Thomas H. Osborne ◽

Matthew D. Heath ◽

Andrew C. R. Martin ◽

Jaroslaw A. Pankowski ◽

Karen A. Hudson-Edwards ◽

...

Keyword(s):

Arsenite Oxidase ◽

Cold Adapted

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Identification of a Novel Arsenite Oxidase Gene, arxA, in the Haloalkaliphilic, Arsenite-Oxidizing Bacterium Alkalilimnicola ehrlichii Strain MLHE-1

Journal of Bacteriology ◽

10.1128/jb.00244-10 ◽

2010 ◽

Vol 192 (14) ◽

pp. 3755-3762 ◽

Cited By ~ 88

Author(s):

Kamrun Zargar ◽

Shelley Hoeft ◽

Ronald Oremland ◽

Chad W. Saltikov

Keyword(s):

Genetic System ◽

Mono Lake ◽

Genetic Identification ◽

Transcription Analysis ◽

Oxidase Gene ◽

Arsenite Oxidation ◽

Dmso Reductase ◽

Arsenite Oxidase ◽

New Type

ABSTRACT Although arsenic is highly toxic to most organisms, certain prokaryotes are known to grow on and respire toxic metalloids of arsenic (i.e., arsenate and arsenite). Two enzymes are known to be required for this arsenic-based metabolism: (i) the arsenate respiratory reductase (ArrA) and (ii) arsenite oxidase (AoxB). Both catalytic enzymes contain molybdopterin cofactors and form distinct phylogenetic clades (ArrA and AoxB) within the dimethyl sulfoxide (DMSO) reductase family of enzymes. Here we report on the genetic identification of a “new” type of arsenite oxidase that fills a phylogenetic gap between the ArrA and AoxB clades of arsenic metabolic enzymes. This “new” arsenite oxidase is referred to as ArxA and was identified in the genome sequence of the Mono Lake isolate Alkalilimnicola ehrlichii MLHE-1, a chemolithoautotroph that can couple arsenite oxidation to nitrate reduction. A genetic system was developed for MLHE-1 and used to show that arxA (gene locus ID mlg_0216) was required for chemoautotrophic arsenite oxidation. Transcription analysis also showed that mlg_0216 was only expressed under anaerobic conditions in the presence of arsenite. The mlg_0216 gene is referred to as arxA because of its greater homology to arrA relative to aoxB and previous reports that implicated Mlg_0216 (ArxA) of MLHE-1 in reversible arsenite oxidation and arsenate reduction in vitro. Our results and past observations support the position that ArxA is a distinct clade within the DMSO reductase family of proteins. These results raise further questions about the evolutionary relationships between arsenite oxidases (AoxB) and arsenate respiratory reductases (ArrA).

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