Aims:  The present study was conducted by screening zein‐degrading bacteria in an attempt to obtain zein‐degrading protease. Methods and Results:  Soil bacteria were screened by formation of a clear zone on zein plates. Characterization of a zein‐degrading bacterium indicated a taxonomic affiliation to Bacillus pumilus, and was named MS‐1 strain. The strain produced two different types of extracellular proteases, BPP‐A and BPP‐B. In this study, we purified and characterized BPP‐A because it exhibited a higher ability to hydrolyze zein than BPP‐B. When casein was used as the substrate, the optimal pH for BPP‐A was 11·0. In BPP‐A, zein was better substrate than casein at pH 13·0, whereas casein was better one than zein at pH 11·0. The bppA gene encoded a 383‐amino acid pre‐pro form of BPP‐A, and mature BPP‐A contained 275 amino acid residues. It was concluded that BPP‐A belonged to the subtilisin family. Conclusion:  A zein‐degrading bacterium assigned to B. pumilus produced two different types of extracellular proteases, BPP‐A and BPP‐B. BPP‐A exhibited an ability to hydrolyze zein in an extreme alkaline condition. Significance and Impact of the Study:  This is a first report on screening for zein‐degrading micro‐organisms. The subtilisin‐like protease BPP‐A is possible to utilize as an industrial enzyme for the production of zein hydrolysates.

Aims:  The present study was conducted by screening soil bacteria in an attempt to isolate a bacterium that produced extracellular alkaline protease, and for purification and characterization of the protease. Methods and Results:  Soil bacteria were screened by growth on casein as the sole carbon source. Characterization of a strain isolated from soil of Abashiri, Japan indicated a taxonomic affiliation to Stenotrophomonas maltophilia, and was named S‐1 strain. The purified S‐1 protease, designed S. maltophilia Protease‐1 (SmP‐1), exhibited an optimal pH of 12·0, optimal reaction temperature of 50°C and a molecular mass of approximately 40 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE). The cleavage sites of the oxidized‐insulin B chain by SmP‐1 were identified as Leu6‐Cys7, Cys7‐Gly8, Tyr16‐Leu17 and Leu17‐Val18. The N‐terminal amino acid sequence of the purified alkaline protease was determined as NH2‐SASAPMVSGVAALVLE. Conclusion:  A novel extracellular alkaline serine protease was isolated from S. maltophilia strain S‐1. The optimal pH of the proteolytic activity was pH 12·0. Significance and Impact of the Study:  The extremely high optimal pH and heat stability of the alkaline serine protease SmP‐1 might make it widely applicable to food and other industries.

PDB Reference: selenophosphate synthetase, 2zau, r2zausf.Selenophosphate synthetase (SPS) catalyzes the activation of selenide with ATP to synthesize selenophosphate, the reactive selenium donor for biosyntheses of both the 21st amino acid selenocysteine and 2-selenouridine nucleotides in tRNA anticodons. The crystal structure of an N-terminally (25 residues) truncated fragment of SPS (SPS-ÁN) from Aquifex aeolicus has been determined at 2.0 Å resolution. The structure revealed SPS to be a two-domain / protein, with domain folds that are homologous to those of PurMsuperfamily proteins. In the crystal, six monomers of SPS-ÁN form a hexamer of 204 kDa, whereas the molecular weight estimated by ultracentrifugation was $63 kDa, which is comparable to the calculated weight of the dimer (68 kDa).

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