COMPARATIVE ANALYSIS OF GLYCOGEN SYNTHESIS ENZYMES IN CYANOBACTERIA

MARTÍNEZ NOËL G; GIARROCO L; SALERNO G

Congreso; SAIB 2011; 2011

Plants, green algae, and cyanobacteria (CN) synthesize storage polysaccharides by a similar ADPG-based pathway. CN, as other bacteria, accumulates glycogen, while plants and algae synthesized starch. Glycogen and starch synthesis are very complex processes. Each group present special features, but the two first steps, carried out by ADP-glucose pyrophosphorylase (AGPase) and glycogen synthase (GS)/starch synthase, are present in all organisms. CN represent a very interesting group because storage metabolism pathways of photosynthetic eukaryotes have evolved from a cyanobacterial ancestor via endosymbiosis. Thus, we perform a global comparative bioinformatic analysis of all AGPase and GS proteins of cyanobacterial available genomes and representative sequences of Viridiplantae and Bacteria with the aim of detecting key diversity patterns that could reflect functional differences. The results reveal that all CN have a single AGPase, which is extremely conserved within this group. However, cyanobacterial GS presents major variability and one or two isoforms (GSA1 and GSA2), with the exception of UCYN-A, which lacks GS homologs. GSA1 is found in almost all CN analyzed, however GSA2 is only found in 25/58 genomes. The most important differences in domains, 3D structure and phylogeny related with protein function will be discussed. Supported by PIP 134, UNMdP (EXA553) and FIBA.