Abstract
Clostridium taeniosporum, a non-pathogenic anaerobe closely related to the C. botulinum Group II members, was isolated from Crimean lake silt about 60 years ago. Its endospores are surrounded by an encasement layer which forms a trunk at one spore pole to which about 12–14 large, ribbon-like appendages are attached. The genome consists of one 3,264,813 bp, circular chromosome (with 26.6% GC) and three plasmids. The chromosome contains 2,892 potential protein coding sequences: 2,124 have specific functions, 147 have general functions, 228 are conserved but without known function and 393 are hypothetical based on the fact that no statistically significant orthologs were found. The chromosome also contains 101 genes for stable RNAs, including 7 rRNA clusters. Over 84% of the protein coding sequences and 96% of the stable RNA coding regions are oriented in the same direction as replication. The three known appendage genes are located within a single cluster with five other genes, the protein products of which are closely related, in terms of sequence, to the known appendage proteins. The relatedness of the deduced protein products suggests that all or some of the closely related genes might code for minor appendage proteins or assembly factors. The appendage genes might be unique among the known clostridia; no statistically significant orthologs were found within other clostridial genomes for which sequence data are available. The C. taeniosporum chromosome contains two functional prophages, one Siphoviridae and one Myoviridae, and one defective prophage. Three plasmids of 5.9, 69.7 and 163.1 Kbp are present. These data are expected to contribute to future studies of developmental, structural and evolutionary biology and to potential industrial applications of this organism.
Highlights
Bacterial endospore appendages are both common and highly diverse in structure, including ribbons, pili, feathers, brushes, tubules and swords
This organism, a Gram-positive, non-pathogenic anaerobe isolated from Crimean lake silt, is unique because its spores are surrounded by a thick "encasement" layer which forms a trunk at one spore pole from which about 12–14, large, flat, ribbon-like appendages emanate [3, 4, 5, 6]
The C. taeniosporum genome consists of a single circular chromosome of 3.26 Mbp, including two prophages and one defective prophage, plus three plasmids and includes numerous genes which code for proteins related to mobile elements, all suggesting that this organism has undergone many genetic exchanges
Summary
Bacterial endospore appendages are both common and highly diverse in structure, including ribbons, pili, feathers, brushes, tubules and swords (reviewed in [1, 2]). Their formation is highly variable even among closely related organisms. Of special interest are the spore appendages of Clostridium taeniosporum This organism, a Gram-positive, non-pathogenic anaerobe isolated from Crimean lake silt, is unique because its spores are surrounded by a thick "encasement" layer which forms a trunk at one spore pole from which about 12–14, large, flat, ribbon-like appendages emanate [3, 4, 5, 6]. Each ribbon contains about 50,000 to 100,000 complexes and the complete set of appendages is assembled from about 600,000 to 1,200,000 molecules of each of the principal component proteins
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