Cytoplasmic helical structure associated with Acholeplasma laidlawii

Abstract

A distinct spiral protein structure was found in three species of Acholeplasma, but was not found in the Mycoplasma species studied. The spirals, which are 14 nm in width and of variable length from 50 to 300 nm, are formed by a helical arrangement of 7-nm subunits. A rosette-like structure 45 nm in diameter also composed of 7-nm subunits was found in close association with the spirals and may be a taut in vivo form of the spiral. The electrophoretic profile in sodium dodecyl sulfate-polyacrylamide gels indicated that the spirals are composed of a predominant polypeptide with an apparent molecular weight of 100,000. No evidence can be found for inferring actin-like properties for this structure. 353 on July 16, 2020 by guest

Comparative Characterization of Spirosomes Isolated from Lactobacillus brevis, Lactobacillus fermentum, and Lactobacillus buchneri

“…or similar spiral structures have been demonstrated electron microscopically in a variety of gram-positive and -negative bacteria such as the genera, Lactobacillus (12,13), Clostridium (23, 28), Listeria (1), Peptostreptococcus (21), Eubacterium (21), Escherichia (14) , Salmonella (11), Shigella (11), Enterobacter (11) , Yersinia (11), Spirochaeta (6), Treponema (8), and Acholeplasma (16). The spirosomes of L. brevis were produced spontaneously at any stage of growth and mitomycin C did not cause an increase in the number of spirosomes (13).…”

“…Matayoshi and Oda (21) also suggested that the spirosomes are present on the cell wall in some bacteria as well as in the cytoplasm since they could be released in a bacterial cell suspension treated by weak sonication in spite of the fact that most of the cells were not disrupted. On the other hand, we have considered that the spirosomes exist as spiral inclusions within the cytoplasm because they were obtained from protoplasts or spheroplasts (13,14) and from A. laidlawii, a cell wall-free organism (16), after osmotic lysis. Although the spirosomes isolated from some bacteria were found to be composed of a single protein with the molecular weight of about 94,000 to 100,000 (11), the detailed biochemical properties and functions of the spirosomes have not yet been investigated except for the spirosomes of L. brevis (15,29) and A. laidlawii (16).…”

“…digestion and composed of a single protein, termed spirosin, with an apparent molecular weight of about 95,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) (29). Similar cytoplasmic helical structures were isolated from Acholeplasma laidlawii and were found to be composed of a predominant polypeptide with a molecular weight of 100,000 (16). Matayoshi and Oda (21) also reported that spirosomes morphologically indistinguishable from one another were isolated from nine gram-positive bacteria including Peptostreptococcus productus and Eubacterium aerofaciens after weak sonication and that they were composed of one main protein with a molecular weight of about 94,000 to 95,000.…”

Detection of Fine Spiral Structures (Spirosomes) by Weak Sonication in Some Bacterial Strains

“…The difference in the molecular weight among these spirosomes was not very great but there were slight differences according to the strains from which the spirosomes were derived. The spirosomes of L. brevis have been reported to consist of only a single protein with an apparent molecular weight of about 95,000 (12) and the spirosome of A. laidlawii is said to be composed of a predominant portion with a molecular weight of 100,000 (7). Thus, the spiral structures termed spirosomes resemble each other in their morphology and molecular weight, but it is not clear whether these spirosomes are essentially similar in their nature and biological function or whether these helical structures are normal in the cell.…”

“…Ueda and Takagi (11) found similar spiral structures in mitomycin-induced lysates of Clostridium botulinu m type B. Kawata et al (6) found similar particles in the mesosomal fraction obtained from protoplasts of Lactobacillus fermenti and Lactobacillus casei by osmotic disruption and named the particle "spirosome." Since then, spirosomes or similar particles have been observed in both gram-positive and gram-negative bacteria (4,5,7,9). However their true origin and function are still obscure.…”