Deoxyribonucleic acid in Nitrobacter carboxysomes

Bacterial microcompartment organelles: protein shell structure and evolution

Some bacteria contain organelles or microcompartments consisting of a large virion-like protein shell encapsulating sequentially acting enzymes. These organized microcompartments serve to enhance or protect key metabolic pathways inside the cell. The variety of bacterial microcompartments provide diverse metabolic functions, ranging from CO(2) fixation to the degradation of small organic molecules. Yet they share an evolutionarily related shell, which is defined by a conserved protein domain that is widely distributed across the bacterial kingdom. Structural studies on a number of these bacterial microcompartment shell proteins are illuminating the architecture of the shell and highlighting its critical role in controlling molecular transport into and out of microcompartments. Current structural, evolutionary, and mechanistic ideas are discussed, along with genomic studies for exploring the function and diversity of this family of bacterial organelles.

Isolation and characterization of a carboxysome shell gene from Thiobacillus neapolitanus

The gene coding for the major carboxysome shell peptide (csoS1) from Thiobacillus neapolitanus has been isolated and sequenced. Oligonucleotide primers for polymerase chain reaction (PCR) amplification of the 5' end of the gene were made possible by amino acid sequencing of the N-terminal residues of the shell peptide. A 41 bp PCR product was used as a probe to isolate the gene. The deduced amino acid composition of the 216 bp gene shows a high degree of hydrophobicity. The gene is located within a series of three repeated regions of DNA and appears to have arisen via gene duplication. The transcript of csoS1 is approximately 400 bases in length. The shell peptide shares significant homology with Synechococcus open reading frames implicated in carboxysome structure/assembly. These open reading frames and csoS1 are related and are probably members of a carboxysome gene family.

Molecular and cellular regulation of autotrophic carbon dioxide fixation in microorganisms

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Ecophysiological studies on Spirulina platensis. Effect of temperature, light intensity and nitrate concentration on growth and ultrastructure

The ultrastructure of the cyanobacterium Spirulina platensis was studied in relation to temperature, light intensity and nitrate concentration. The organism was able to grow in media supplied with nitrate in concentrations up to 250 mM. High nitrate concentrations increased the yield and growth rate at temperatures above 35 degeees C. Occurrence, distribution and abundance of cyanophycin granules, polyglucan granules, cylindrical bodies, carboxysomes and mesosomes varied widely in relation to the factors studied. At low temperatures (up to 17 degrees C) cyanophycin was the abundant organelle, especially at high nitrate concentrations, whereas in the temperature range 17--20 degrees C polyglucan was found in large quantities particularly at low nitrate concentrations. Special attention was paid to the cylindrical bodies, the ultrastructure of which was dependent on temperature. Three types of ultrastructure were distinguished each with several possible shapes.