Previous Article | Next Article ![]()
Journal of Bacteriology, August 1998, p. 4133-4139, Vol. 180, No. 16
Department of Biological Sciences, Clemson
University, Clemson, South Carolina 29634,1
and
Department of Microbiology and Cell Science, University of
Florida, Gainesville, Florida 32611-01162
Received 24 March 1998/Accepted 4 June 1998
It has been previously established that Thiobacillus
neapolitanus fixes CO2 by using a form I
ribulose bisphosphate carboxylase/oxygenase (RuBisCO), that
much of the enzyme is sequestered into carboxysomes, and that the genes
for the enzyme, cbbL and cbbS, are part of a
putative carboxysome operon. In the present study, cbbL and cbbS were cloned and sequenced. Analysis of RNA showed that
cbbL and cbbS are cotranscribed on a message
approximately 2,000 nucleotides in size. The insertion of a kanamycin
resistance cartridge into cbbL resulted in a premature
termination of transcription; a polar mutant was generated. The mutant
is able to fix CO2, but requires a CO2
supplement for growth. Separation of cellular proteins from both the
wild type and the mutant on sucrose gradients and subsequent analysis of the RuBisCO activity in the collected fractions showed that
the mutant assimilates CO2 by using a form II RuBisCO. This was confirmed by immunoblot analysis using antibodies raised
against form I and form II RuBisCOs. The mutant does not possess
carboxysomes. Smaller, empty inclusions are present, but biochemical
analysis indicates that if they are carboxysome related, they are
not functional, i.e., do not contain RuBisCO. Northern
analysis showed that some of the shell components of the carboxysome
are produced, which may explain the presence of these inclusions in the
mutant.
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Insertion Mutation of the Form I cbbL Gene
Encoding Ribulose Bisphosphate Carboxylase/Oxygenase (RuBisCO)
in Thiobacillus neapolitanus Results in Expression of
Form II RuBisCO, Loss of Carboxysomes, and an Increased
CO2 Requirement for Growth

and
*
Corresponding author. Mailing address: Department of
Biological Sciences, 132 Long Hall, Clemson University, Clemson,
SC 29634. Phone: (864) 656-3595. Fax: (864) 656-0435. E-mail:
SJESSUP{at}CLEMSON.EDU.
Present address: Department of Environmental Biology, University of
Guelph, Guelph, Ontario N1G2W1, Canada.
Present address: Department of Biological Sciences, Southeastern
Louisiana University, Hammond, LA 40402.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»