  The unicellular cyanobacterium Synechococcus PCC 7942 has been used as a
model organism for studies of prokaryotic circadian rhythms,
carbon-concentrating mechanisms, response to a variety of nutrient and
environmental stresses, and cell division. This paper presents the results of
the first proteomic exploratory study of Synechococcus PCC 7942. The proteome
was analyzed using two-dimensional gel electrophoresis followed by MALDI-TOF
mass spectroscopy, and database searching. Of 140 analyzed protein spots, 110
were successfully identified as 62 different proteins, many of which occurred
as multiple spots on the gel. The identified proteins were organized into 18
different functional categories reflecting the major metabolic and cellular
processes occurring in the cyanobacterial cells in the exponential growth
phase. Among the identified proteins, 14 previously unknown or considered to be
hypothetical are here shown to be true gene products in Synechococcus sp. PCC
7942, and may be helpful for annotation of the newly sequenced genome.
