BA41, A NOVEL TPM-DOMAIN ATPASE FROM THE ANTARTIC FLAVOBACTERIUM Bizionia argentinensis

CERUTTI ML; OTERO LH; SMAL CA; GOLDBAUM FA; ARÁN M; KLINKE S

Congreso; - SAIB - 51 Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2015

The genome of the psychrophilic flavobacterium Bizionia argentinensis (Ba) was recently decoded. In order to tackle a structural coverage and accurate functional annotation of the Ba genome, we selected and expressed a set of domains with unknown function. BA41 is a member of the broadly conserved TPM domain family found across prokaryotes, plants and invertebrates. It is comprised by an N-terminal signal peptide, a single globular TPM domain followed by a transmembrane region and a C-terminal low complexity region. We´ve previously solved the crystal structure of the central TPM domain and found that it displays a Rossmann fold similar to an acid phosphatase from A. thaliana and other two uncharacterized prokaryotic domains. The structure revealed a Zn2+ atom in the putative active site, but this metal was also present in the crystallization conditions. We now present a new X-ray tridimensional structure obtained at near atomic resolution (1.4 Å) and show that this domain does not contains a structural metal. Functional assays showed that BA41 has a marginal reactivity against P-serine and cannot hydrolyze the general pNPP phosphatase substrate. Interestingly, the BA41 TPM domain displays high hydrolase activity against ATP and ADP and other triphosphate nucleotides, suggesting that this protein may represent a new class of the broad nucleotide specific ecto-NTPDases family.