A network of genes regulated by light in cyanobacteria

OMICS. Summer 2007;11(2):166-85. doi: 10.1089/omi.2007.4323.

Abstract

Oxygenic photosynthetic organisms require light for their growth and development. However, exposure to high light is detrimental to them. Using time series microarray data from a model cyanobacterium, Synechocystis 6803 transferred from low to high light, we generated a gene co-expression network. The network has twelve sub-networks connected hierarchically, each consisting of an interconnected hub-and-spoke architecture. Within each sub-network, edges formed between genes that recapitulate known pathways. Analysis of the expression profiles shows that the cells undergo a phase transition 6-hours post-shift to high light, characterized by core sub-network. The core sub-network is enriched in proteins that (putatively) bind Fe-S clusters and proteins that mediate iron and sulfate homeostasis. At the center of this core is a sulfate permease, suggesting sulfate is rate limiting for cells grown in high light. To validate this novel finding, we demonstrate the limited ability of cell growth in sulfate-depleted medium in high light. This study highlights how understanding the organization of the networks can provide insights into the coordination of physiologic responses.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Cyanobacteria / cytology
  • Cyanobacteria / genetics
  • Cyanobacteria / metabolism*
  • Gene Expression Profiling*
  • Gene Expression Regulation, Bacterial
  • Genome, Bacterial*
  • Light
  • Models, Biological