Two relA/spoT homologous genes are involved in the morphological and physiological differentiation of Streptomyces clavuligerus

Microbiology. 2004 May;150(Pt 5):1485-1493. doi: 10.1099/mic.0.26811-0.


This study is focused on the involvement of the unusual nucleotide (p)ppGpp during the morphological and physiological differentiation of Streptomyces clavuligerus. In particular, the functional and structural elements of two genes encoding the proteins RelA and Rsh were identified. The relA gene encodes an 843 aa protein (RelA), while the rsh gene encodes a 738 aa protein (Rsh). The relA and rsh genes were disrupted by the insertion of a hygromycin resistance gene and an apramycin resistance gene, respectively. The synthesis of ppGpp in the relA gene-disrupted mutant was completely eliminated under conditions of starvation for amino acids, whereas synthesis persisted, but was greatly reduced in the rsh gene-disrupted mutant. The relA gene-disrupted mutant had a bald appearance on agar plate cultures and retarded growth in submerged culture, while the rsh-disrupted mutant was unchanged in growth characteristics relative to the wild-type culture. The production of both clavulanic acid and cephamycin C were completely abolished in the relA-disrupted mutant. Thus, it is concluded that the relA gene rather than rsh is essential for morphological and physiological differentiation in S. clavuligerus and that RelA primarily governs the stringent response of S. clavuligerus to starvation for amino acids.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Cephamycins / biosynthesis
  • Clavulanic Acid / biosynthesis
  • Culture Media
  • Gene Expression Regulation, Bacterial*
  • Genetic Complementation Test
  • Guanosine Pentaphosphate / metabolism
  • Guanosine Tetraphosphate / metabolism
  • Ligases / genetics*
  • Ligases / metabolism
  • Molecular Sequence Data
  • Mutation
  • Phylogeny
  • Sequence Analysis, DNA
  • Streptomyces / genetics
  • Streptomyces / growth & development*
  • Streptomyces / physiology*


  • Bacterial Proteins
  • Cephamycins
  • Culture Media
  • RshA protein, Streptomyces coelicolor
  • Clavulanic Acid
  • Guanosine Tetraphosphate
  • Guanosine Pentaphosphate
  • Ligases
  • guanosine 3',5'-polyphosphate synthetases
  • cephamycin C

Associated data

  • GENBANK/AJ421216
  • GENBANK/AJ421217