RUBISCO BUT NOT RUBISCO ACTIVASE IS CLUSTERED IN THE CARBOXYSOMES OF THE CYANOBACTERIUM SYNECHOCOCCUS SP PCC-7942 - MUD-INDUCED CARBOXYSOMELESS MUTANTS
D. Friedberg et al., RUBISCO BUT NOT RUBISCO ACTIVASE IS CLUSTERED IN THE CARBOXYSOMES OF THE CYANOBACTERIUM SYNECHOCOCCUS SP PCC-7942 - MUD-INDUCED CARBOXYSOMELESS MUTANTS, Molecular microbiology, 9(6), 1993, pp. 1193-1201
The Mud technology of Groisman and Casadaban was adapted to the cyanob
acterium Synechococcus sp. PCC 7942. A new high-CO2-requiring (hcr) mu
tant, hcr Mu28 was isolated following the integration of the Mud eleme
nt 89 bp upstream of ORFI, at the 5'-flanking region of the rbc operon
, which encodes RuBP carboxylase/oxygenase (Rubisco). The integration
involved a 7 bp duplication that formed a direct repeat at the integra
tion site, as previously shown in Escherichia coli. The mutant was dev
oid of apparent carboxysome bodies, which are considered to be importa
nt for the availability of CO2 for Rubisco. Immunolabelling studies de
monstrated that Rubisco was distributed throughout hcr Mu28 cells, whi
le in the wild type (WT) and in the carboxysome aberrant mutant hcr O2
21, Rubisco was markedly associated with the carboxysomes. Rubisco act
ivase, however, was evenly distributed throughout the cytosol of the h
cr and WT cells, without any preferential association with the apparen
t carboxysomes.