The novel extracellular Streptomyces reticuli haem-binding protein HbpS influences the production of the catalase-peroxidase CpeB

• Published in: Microbiology (Society for General Microbiology) 2004-08, Vol.150 (8), p.2575-2585
• Main Authors: Lucana, Dario Ortiz de Orue, Schaa, Tanja, Schrempf, Hildgund
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Bacterial plant pathogens; Bacterial Proteins - biosynthesis; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriological methods and techniques used in bacteriology; Bacteriology; Base Sequence; Biological and medical sciences; Carrier Proteins - genetics; Carrier Proteins - metabolism; Chromosome Mapping; Cloning, Molecular; DNA, Bacterial - genetics; Escherichia coli; Escherichia coli - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression; Genes, Bacterial; Heme-Binding Proteins; Hemeproteins - genetics; Hemeproteins - metabolism; Microbiology; Miscellaneous; Molecular Sequence Data; Mutagenesis, Site-Directed; Peroxidases - biosynthesis; Peroxidases - genetics; Phytopathology. Animal pests. Plant and forest protection; Protein Sorting Signals; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Sequence Homology, Amino Acid; Streptomyces - genetics; Streptomyces - metabolism; Streptomyces lividans; Streptomyces reticuli
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/mic.0.27091-0

Universität Osnabrück, FB Biologie/Chemie, Barbarastraße 11, D-49069 Osnabrück, Germany Correspondence Darío Ortiz de Orué Lucana ortiz{at}biologie.uni-osnabrueck.de The Gram-positive soil bacterium and cellulose degrader Streptomyces reticuli synthesizes the mycelium-associated enzyme CpeB, which displays haem-dependent catalase and peroxidase activity, as well as haem-independent manganese-peroxidase activity. Downstream of the cpeB gene, a so far unknown gene was identified. The new gene and its mutated derivatives were cloned in Escherichia coli as well as in Streptomyces lividans and a gene-disruption mutant within the chromosome of the original S. reticuli host was constructed, comparative physiological, biochemical and immunological studies then allowed the deduction of the following characteristics of the novel gene product. (i) The protein was found extracellularly; the substitution of twin arginines within the signal peptide abolished its secretion. (ii) The highly purified protein interacted specifically with haem and hence was designated HbpS (haem-binding protein of Streptomyces ). (iii) HbpS contained three histidine residues surrounded by hydrophobic amino acids; one of them was located within the motif LX 3 THLX 10 AA, which is related to the motif within the yeast cytochrome c peroxidase LX 2 THLX 10 AA whose histidine residue interacts with haem. (iv) The addition of haemin (Fe 3+ oxidized form of haem) to the Streptomyces cultures led to enhanced levels of HbpS which correlated with increased haemin-resistance. (v) The presence of HbpS increased synthesis of the highly active catalase-peroxidase CpeB containing haem. In this process HbpS could act as a chaperone that binds haem and then delivers it to the mycelium-associated CpeB; HbpS could also interact with membrane-associated proteins involved in a signal transduction cascade regulating the expression of cpeB . (vi) HbpS shared varying degrees of amino acid identities with bacterial proteins of so far unknown function. This report contributes to the elucidation of the biological function of these proteins. The GenBank/EMBL/DDBJ accession number for the sequence of hbpS from Streptomyces reticuli reported in this paper is Y14336 .