Beta-propeller phytases in the aquatic environment

Arch Microbiol. 2006 Mar;185(1):1-13. doi: 10.1007/s00203-005-0080-6. Epub 2006 Jan 10.

Abstract

Phytate, which is one of the dominant organic phosphorus compounds in nature, is very stable in soils. Although a substantial amount of phytate is carried from terrestrial to aquatic systems, it is a minor component of organic phosphorus in coastal sediments. The ephemeral nature of phytate implies the rapid hydrolysis of phytate under aquatic conditions. Among the four classes of known phytases that have been identified in terrestrial organisms, only beta-propeller phytase-like sequences have been identified in the aquatic environment. A novel beta-propeller phytase gene (phyS), cloned from Shewanella oneidensis MR-1, was found to encode a protein with two beta-propeller phytase domains. The characterization of recombinant full-length PhyS and its domains demonstrated that Domain II was the catalytic domain responsible for phytate hydrolysis. The full-length PhyS displayed a K(m) of 83 microM with a kcat of 175.9 min(-1) and the Domain II displayed a K(m) of 474 microM with a kcat of 10.6 min(-1). These results confirm that the phyS gene encodes a functional beta-propeller phytase, which is expressed in S. oneidensis under phosphorus deficient condition. The presence of multiple sequences with a high similarity to phyS in aquatic environmental samples and the widespread occurrence of the Shewanella species in nature suggest that the beta-propeller phytase family is the major class of phytases in the aquatic environment, and that it may play an important role in the recycling of phosphorus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 6-Phytase / chemistry
  • 6-Phytase / genetics*
  • 6-Phytase / metabolism
  • Amino Acid Sequence
  • Bacillus subtilis / enzymology
  • Bacillus subtilis / genetics
  • Base Sequence
  • Molecular Sequence Data
  • Phosphorus / chemistry*
  • Phylogeny
  • Phytic Acid / chemistry*
  • Protein Structure, Tertiary
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Seawater / microbiology
  • Shewanella / enzymology*
  • Shewanella / genetics
  • Water Microbiology*

Substances

  • Recombinant Proteins
  • Phosphorus
  • Phytic Acid
  • 6-Phytase