Identification by shotgun sequencing, genomic organization, and functional analysis of a fourth arylsulfatase gene (ARSF) from the Xp22.3 region
GENOMICS
Authors: Puca, AA; Zollo, M; Repetto, M; Andolfi, G; Guffanti, A; Simon, G; Ballabio, A; Franco, B
Abstract
We recently reported the isolation of two new members of the sulfatase gene family, arylsulfatase D (ARSD) and E (ARSE), located approximately 50 kb from each other in the Xp22.3 region, Mutation analysis indicated ARSE as the gene responsible for X-linked recessive chondrodysplasia punctata. Expression of the ARSE gene in COS cells resulted ina heat-labile arylsulfatase activity that was inhibited by warfarin, At the same time, we detected the presence of a 1.2-kb fragment located at similar to 60 kb from ARSD and ARSE with significant homology to these two genes, suggesting the existence of another sulfatase gene, arylsulfatase F (ARSF), in Xp22.3. We have used a combined approach of long-range genomic sequencing and screening of cDNA libraries to isolate the ARSE gene. Expression of the ARSE cDNA in COS cells resulted in a heat-labile arylsulfatase activity that is not inhibited by warfarin, supporting our hypothesis that only ARSE is specifically inhibited by warfarin and is most likely involved in warfarin embryopathy. Genomic analysis revealed that ARSE has an intron/exon organization highly similar to those of ARSD and ARSE, which is also shared by another Xp22.3 sulfatase gene, ARSC (arylsulfatase C, also known as steroid sulfatase), with the splice sites occurring at the same position in all four genes. The data obtained from sequence analysis and presented in this paper indicate that the ARSC, ARSD, ARSE, and ARSF genes are more similar to each other than to other members of the sulfatase gene family, supporting our hypothesis that they represent a subfamily of related proteins created through duplication events that occurred in an ancestral pseudoautosomal region. (C) 1997 Academic Press.
Role of ArsEFG in Roxarsone and Nitarsone Detoxification and Resistance
ENVIRONMENTAL SCIENCE & TECHNOLOGY
Authors: Chen, Jian; Zhang, Jun; Rosen, Barry P.
Abstract
Organoarsenical biotransformations are important components of the global cycling of arsenic. Roxarsone (3-nitro-4-hydroxybenzenearsenate or Rox(V)) and nitarsone (4-nitrobenzene arsenate or Nit(V)) are synthetic aromatic organoarsenicals used in the poultry industry as additives to prevent coccidiosis and improve feed efficiency. Here, we describe a novel pathway of resistance to roxarsone and nitarsone involving biotransformation of their trivalent forms (Rox(III)) and (Nit(III)) to the trivalent organoarsenicals HAPA(III) and pAsA(III), coupled to active extrusion of the aromatic amino-benezylarsenicals from the cells. The arsE, arsF, and arsG were cloned from the arsenic island in the chromosome of Shewanella putrefaciens 200. When expressed in Escherichia coli together, but not alone, arsEFG conferred resistance to Rox(III) and Nit(III) and decreased the accumulation of both. The cells transformed Rox(III) or Nit(III) to HAPA(III) or pAsA(III) by reducing the nitro group to an amine. Everted membrane vesicles from cells expressing arsG accumulated HAPA(III) or pAsA(III). Our data indicate that ArsE and ArsF together reduce Rox(III) or Nit(III) to HAPA(III) or pAsA(III), which are extruded from the cells by the efflux permease ArsG. Identification of the coupled pathway of ArsE, ArsF, and ArsG catalysis is a molecular description of a novel pathway for resistance to roxarsone and nitarsone.