pubmed.ncbi.nlm.nih.gov

Metabolic streamlining in an open-ocean nitrogen-fixing cyanobacterium - PubMed

  • ️Fri Jan 01 2010

. 2010 Mar 4;464(7285):90-4.

doi: 10.1038/nature08786. Epub 2010 Feb 21.

Affiliations

Metabolic streamlining in an open-ocean nitrogen-fixing cyanobacterium

H James Tripp et al. Nature. 2010.

Abstract

Nitrogen (N(2))-fixing marine cyanobacteria are an important source of fixed inorganic nitrogen that supports oceanic primary productivity and carbon dioxide removal from the atmosphere. A globally distributed, periodically abundant N(2)-fixing marine cyanobacterium, UCYN-A, was recently found to lack the oxygen-producing photosystem II complex of the photosynthetic apparatus, indicating a novel metabolism, but remains uncultivated. Here we show, from metabolic reconstructions inferred from the assembly of the complete UCYN-A genome using massively parallel pyrosequencing of paired-end reads, that UCYN-A has a photofermentative metabolism and is dependent on other organisms for essential compounds. We found that UCYN-A lacks a number of major metabolic pathways including the tricarboxylic acid cycle, but retains sufficient electron transport capacity to generate energy and reducing power from light. Unexpectedly, UCYN-A has a reduced genome (1.44 megabases) that is structurally similar to many chloroplasts and some bacteria, in that it contains inverted repeats of ribosomal RNA operons. The lack of biosynthetic pathways for several amino acids and purines suggests that this organism depends on other organisms, either in close association or in symbiosis, for critical nutrients. However, size fractionation experiments using natural populations have so far not provided evidence of a symbiotic association with another microorganism. The UCYN-A cyanobacterium is a paradox in evolution and adaptation to the marine environment, and is an example of the tight metabolic coupling between microorganisms in oligotrophic oceanic microbial communities.

PubMed Disclaimer

Similar articles

Cited by

References

    1. DNA Res. 1995 Jun 30;2(3):133-42 - PubMed
    1. Bioinformatics. 2008 Dec 15;24(24):2818-24 - PubMed
    1. Appl Environ Microbiol. 2002 Nov;68(11):5760-4 - PubMed
    1. J Plant Physiol. 2003 Jan;160(1):33-9 - PubMed
    1. Nucleic Acids Res. 2008 Jan;36(Database issue):D528-33 - PubMed

Publication types

MeSH terms

Substances

LinkOut - more resources