title: SSoNDelta and SSoNDeltalong: two thermostable esterases from the same ORF in the archaeon Sulfolobus solfataricus?
abstract: Previously, we reported from the Sulfolobus solfataricus open reading frame (ORF) SSO2517 the cloning, overexpression and characterization of an esterase belonging to the hormone-sensitive lipase (HSL) family and apparently having a deletion at the N-terminus, which we named SSoNDelta. Searching the recently reported Sulfolobus acidocaldarius genome by sequence alignment, using SSO2517 as a query, allowed identity of a putative esterase (ORF SAC1105) sharing high sequence similarity (82%) with SSO2517. This esterase displays an N-terminus and total length similar to other known esterases of the HSL family. Analysis of the upstream DNA sequence of SS02517 revealed the possibility of expressing a longer version of the protein with an extended N-terminus; however, no clear translation signal consistent with a longer protein version was detected. This new version of SSO2517 was cloned, over-expressed, purified and characterized. The resulting protein, named SSoNDeltalong, was 15-fold more active with the substrate p-nitrophenyl hexanoate than SSoNDelta. Furthermore, SSoNDeltalong and SSoNDelta displayed different substrate specificities for triacylglycerols. These results and the phylogenetic relationship between S. solfataricus and S. acidocaldarius suggest a common origin of SSO2517 and SAC1105 from an ancestral gene, followed by divergent evolution. Alternatively, a yet-to-be discovered mechanism of translation that directs the expression of SSoNDeltalong under specific metabolic conditions could be hypothesized.
authors.affiliation: Institute of Protein Biochemistry, CNR, Via Pietro Castellino 111, 80131, Naples, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Mandrich
authors.forename: Margherita
authors.initials: M
authors.lastname: Pezzullo
authors.forename: Mosè
authors.initials: M
authors.lastname: Rossi
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Manco
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D043182:Carboxylesterase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D004795:Enzyme Stability; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D016415:Sequence Alignment; D048229:Sulfolobus solfataricus / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D019843:Archaeal Proteins; D043182:Carboxylesterase