title: Multiple small heat shock proteins in rhizobia.
abstract: Seven genes coding for small heat shock proteins (sHsps) in Bradyrhizobium japonicum have been identified. They are organized in five operons that are coordinately regulated by ROSE, a negatively cis-acting DNA element. The deduced sHsps can be divided into two separate classes: class A, consisting of proteins that show similarity to Escherichia coli IbpA and IbpB, and class B, whose members display significant similarity to other sHsps from prokaryotes and eukaryotes. Two-dimensional gel electrophoresis and Edman sequencing revealed the presence of at least 12 sHsps in B. japonicum, indicating a remarkable abundance of sHsps in this organism. Three additional members of class A and two potentially novel heat shock proteins were identified on the basis of their amino termini. The presence of multiple sHsps was also demonstrated for a variety of Rhizobium and Bradyrhizobium species by immunoblot analysis and two-dimensional gel electrophoresis. An extensive database survey revealed that, in contrast to the rhizobia, other bacteria contain maximally two sHsps whereas many plants have been reported to possess a sHsp superfamily.
authors.affiliation: Protein Chemistry Laboratory, Eidgenössische Technische Hochschule, CH-8092 Zürich, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Münchbach
authors.forename: A
authors.initials: A
authors.lastname: Nocker
authors.forename: F
authors.initials: F
authors.lastname: Narberhaus
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D015180:Electrophoresis, Gel, Two-Dimensional; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006360:Heat-Shock Proteins / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D006358:Hot Temperature; D008969:Molecular Sequence Data; D009876:Operon; D012230:Rhizobiaceae / Q000737:chemistry / Q000235:genetics*; D012231:Rhizobium / Q000737:chemistry / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D006360:Heat-Shock Proteins