Fig.3 Overview of membrane associated uptake, efflux/influx, oxidation and reduction of arsenic ion. Arsenic is given more emphasis, as enzymes in the periplasm and cytoplasm are included as well as classes of transporters ArsA/ArsB ATPase efflux/influx pump. The arsB efflux transport systems extend from the cytoplasm across the outer membrane of Gram-negative bacteria. How the substrates affect the efflux/influx systems, that do not have associated with outer membrane protein function, is not known. arsM: arsenite S-adenosylmethyltransferase evolved to methylate arsenic; arsR: first-gene of the lead operon; arsD: second-gene of the lead operon; arsA: arsenic-stimulated ATPase; arsB: arsenic influx/efflux pump and inner membrane; arsAB: arsenic strong pump of coupling influx/efflux and an anion-translocating ATPase; arsC; arsenate to arsenite, reductase gene; arsH: unknown operon of arsenite-oxidizing/reducing; arrA and arrB: arsenate reductase gene; aoxA, aoxB, aoxC, aoxD, aroA and aroB: arsenite oxidation gene.

Fig.3 Sequence alignments of the arsenite-oxidizing bacterial to proteins of the arsB family. The putative arsenic-binding is boldface. P. aeruginosa(ABB016022). P.putida strain OS-5(ABB93931); P.putida strain OS-19(ABB0428); Pseudomonas putida strain RW-28(ABB88574).

Fig.4 Modeling structure of the arsB efflux pump protein. Ribbon diagram of the avtive site of arsenic, shown in yellow, shown in white of arsenic binding enzyme, respectively. (a) OS-5; (b) OS-19; (v) RW-28; (d) arsB influx/efflux. In Fig.4d, schematic representation of arsenic binding to a marginally stable helival peptide containing four Trp, three His and three Arg. SEM images of arsenite-oxidizing bacterial OS-5 (AY952321), RW-28(DQ112333)and OS-19(AY866406) are shown. SEM image illustrate that the cell of strain P.putida are curved rods measured 0.2-1.0㎛ in length and 1.0-5.0㎛ in width.