RESUMEN
The crystal structure of a conserved domain of nonstructural protein 3 (nsP3) from severe acute respiratory syndrome coronavirus (SARS-CoV) has been solved by single-wavelength anomalous dispersion to 1.4 A resolution. The structure of this "X" domain, seen in many single-stranded RNA viruses, reveals a three-layered alpha/beta/alpha core with a macro-H2A-like fold. The putative active site is a solvent-exposed cleft that is conserved in its three structural homologs, yeast Ymx7, Archeoglobus fulgidus AF1521, and Er58 from E. coli. Its sequence is similar to yeast YBR022W (also known as Poa1P), a known phosphatase that acts on ADP-ribose-1''-phosphate (Appr-1''-p). The SARS nsP3 domain readily removes the 1'' phosphate group from Appr-1''-p in in vitro assays, confirming its phosphatase activity. Sequence and structure comparison of all known macro-H2A domains combined with available functional data suggests that proteins of this superfamily form an emerging group of nucleotide phosphatases that dephosphorylate Appr-1''-p.
Asunto(s)
Adenosina Difosfato Ribosa/análogos & derivados , Secuencia Conservada/fisiología , ARN Polimerasa Dependiente del ARN/química , ARN Polimerasa Dependiente del ARN/fisiología , Coronavirus Relacionado al Síndrome Respiratorio Agudo Severo/química , Coronavirus Relacionado al Síndrome Respiratorio Agudo Severo/fisiología , Proteínas no Estructurales Virales/química , Proteínas no Estructurales Virales/fisiología , Adenosina Difosfato Ribosa/metabolismo , Secuencia de Aminoácidos , Datos de Secuencia Molecular , Fosforilación , Estructura Terciaria de Proteína/fisiología , Coronavirus Relacionado al Síndrome Respiratorio Agudo Severo/enzimología , Análisis de Secuencia de Proteína , Relación Estructura-ActividadRESUMEN
Glutathione S-transferases (GSTs) comprise a diverse superfamily of enzymes found in organisms from all kingdoms of life. GSTs are involved in diverse processes, notably small-molecule biosynthesis or detoxification, and are frequently also used in protein engineering studies or as biotechnology tools. Here, we report the high-resolution X-ray structure of Atu5508 from the pathogenic soil bacterium Agrobacterium tumefaciens (atGST1). Through use of comparative sequence and structural analysis of the GST superfamily, we identified local sequence and structural signatures, which allowed us to distinguish between different GST classes. This approach enables GST classification based on structure, without requiring additional biochemical or immunological data. Consequently, analysis of the atGST1 crystal structure suggests a new GST class, distinct from previously characterized GSTs, which would make it an attractive target for further biochemical studies.