Isolation and characterization of high CO sub 2 -requiring mutants of the cyanobacterium Synechococcus PCC7942

Journal Article · Sun Oct 01 04:00:00 EDT 1989 · Plant Physiology; (USA)

DOI:https://doi.org/10.1104/pp.91.2.514· OSTI ID:5857902

Price, G D; Badger, M R ^[1]

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1. Australian National Univ., Canberra (Australia)

A total of 24 high CO{sub 2}-requiring-mutants of the cyanobacterium Synechococcus PCC7942 have been isolated and partially characterized. These chemically induced mutants are able to grow at 1% CO{sub 2}, on agar media, but are incapable of growth at air levels of CO{sub 2}. All the mutants were able to accumulate inorganic carbon (C{sub i}) to levels similar to or higher than wild type cells, but were apparently unable to generate intracellular CO{sub 2}. Compared to wild-type cells, Type I mutants had the following characteristics: fast C{sub i} release, normal internal C{sub i} pool, normal carbonic anhydrase (CA) activity in crude extracts, reduced internal exchange of {sup 18}O from {sup 18}O-labeled CO{sub 2}, 1% CO{sub 2} requirement for growth in liquid media, normal affinity of carboxylase for CO{sub 2}, and long, rod-like carboxysomes. Type II mutants had the following characteristics: slow C{sub i} release, increased internal C{sub i} pool, normal CA activity in crude extracts, normal internal {sup 18}O exchange, a 3% CO{sub 2} requirement for growth in liquid media, high carboxylase activity, normal affinity of carboxylase for CO{sub 2}, and normal carboxysome structure but increased in numbers per cell. Both mutant phenotypes appear to have genetic lesions that result in an inability to convert intracellular HCO{sub 3}{sup {minus}} to CO{sub 2} inside the carboxysome. The features of the type I mutants are consistent with a scenario where carboxysomal CA has been mistargeted to the cytosol. The characteristics of the type II phenotype appear to be most consistent with a scenario where CA activity is totally missing from the cell except for the fact that cell extracts have normal CA activity. Alternatively the Type II mutants may have a lesion in their capacity for H{sup +} import during photosynthesis.

• OSTI ID: 5857902
• Journal Information: Plant Physiology; (USA), Journal Name: Plant Physiology; (USA) Vol. 91:2; ISSN 0032-0889; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBON-CARBON LYASES
CARBOXY-LYASES
CARBOXYLASE
CHALCOGENIDES
CYANOBACTERIA
ENZYMES
EVEN-EVEN NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
LYASES
MICROORGANISMS
MUTANTS
NUCLEI
OXIDES
OXYGEN 18
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
PHYSIOLOGY
STABLE ISOTOPES
TRACER TECHNIQUES