title: New approaches to achieve high level enzyme production in Streptomyces lividans.
abstract: BACKGROUND
  Actinomycetes are saprophytic soil bacteria, and a rich source of industrial enzymes. While some of these enzymes can be produced using well-characterized production platforms such as Escherichia coli or Bacillus subtilis, Streptomyces lividans may be the preferred host for proper folding and efficient secretion of active enzymes. A combination of promoters, signal peptides and hosts were tested in order to obtain the best protein expression in this actinomycete. The xylanase, Xys1, from S. halstedii, the α-amylase, Amy, from S. griseus and the small laccase, SLAC, from S. coelicolor were used as reporters.
  
  
  RESULTS
  The promoters xysAp from S. halstedii JM8 and pstSp from S. lividans were the most efficient among those tested. An improvement of 17 % was obtained in xylanase activity when the signal peptide of the α-amylase protein (Amy) of S. griseus IMRU3570 was used to direct its secretion. Enhanced expression of SsgA, a protein that plays a role in processes that require cell-wall remodelling, resulted in a improvement of 40 and 70 % of xylanase and amylase production, respectively. Deletion of genes SLI7232 and SLI4452 encoding putative repressors of xysAp provided improvement of production up to 70 % in the SLI7232 deletion strain. However, full derepression of this promoter activity was not obtained under the conditions assayed.
  
  
  CONCLUSIONS
  Streptomyces lividans is a frequently used platform for industrial enzyme production and a rational strain-development approach delivered significant improvement of protein production by this host.
authors: Instituto de Biología Funcional y Genómica/Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Salamanca, C/Zacarías González nº 2, 37007, Salamanca, Spain. laura.sevillano@usal.es.
authors: Laura
authors: L
authors: Sevillano
authors: Molecular Biotechnology, IBL, Sylvius Laboratory, Leiden University, Leiden, The Netherlands. vijgenbo@biology.leidenuniv.nl.
authors: Erik
authors: E
authors: Vijgenboom
authors: Molecular Biotechnology, IBL, Sylvius Laboratory, Leiden University, Leiden, The Netherlands. g.wezel@biology.leidenuniv.nl.
authors: Gilles P
authors: GP
authors: van Wezel
authors: Instituto de Biología Funcional y Genómica/Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Salamanca, C/Zacarías González nº 2, 37007, Salamanca, Spain. mardi@usal.es.
authors: Margarita
authors: M
authors: Díaz
authors: Instituto de Biología Funcional y Genómica/Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Salamanca, C/Zacarías González nº 2, 37007, Salamanca, Spain. santa@usal.es.
authors: Ramón I
authors: RI
authors: Santamaría
mesh_terms: D000681:Amylases / Q000096:biosynthesis*; D001426:Bacterial Proteins / Q000378:metabolism; D017353:Gene Deletion; D005818:Genetic Engineering / Q000379:methods*; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D021382:Protein Sorting Signals; D021381:Protein Transport; D012097:Repressor Proteins / Q000378:metabolism; D048170:Streptomyces lividans / Q000201:enzymology*; D014995:Xylosidases / Q000096:biosynthesis*
chemical_list: D001426:Bacterial Proteins; D021382:Protein Sorting Signals; D012097:Repressor Proteins; D000681:Amylases; D014995:Xylosidases