The fine structure of a microplate-microtubule array, microfilaments and polyhedral body associated microtubules in several species of Anabaena

Abstract

A microplate-microtubule array was observed in Anabaena sp. (B-378). This structure consists of an arched plate, about 8 nm thick, and various microtubules, 12 nm in diameter and 50 nm long, arranged in rows. The microtubules project at right angles from one side of the plate into the cytoplasm or towards the plasma membrane. Up to twelve microplate-microtubule arrays were observed in a single section of a cell. Microfilaments, about 2.8 nm in diameter and of undetermined length, were observed in four isolates of Anabaena. The microfilaments were always found in bundles, nwhich varied in size, up to 0.63 mum across and 0.91 mum long. Microtubules, 10 nm in diameter and about 150 nm in length, were observed associated with one facet of polyhedral bodies in 8 out of 20 isolates of Anabaena. The microtubules occurred in groups of up to 20 or more, and were always oriented with the long axis parallel to the facet of a polyhedral body. In cross section, the microtubules had an electron transparent lumen 5 nm wide and a wall 2.5 nm thick. These structures are compared to previously described microtubules and microfilaments.

Carboxysomes: cyanobacterial RubisCO comes in small packages

“…This organization was lost upon deletion of parA (Savage et al 2010), suggesting that parA (which encodes a bacterial cytoskeletal protein) connects adjacent carboxysomes, consistent with earlier reports that fibers are associated with the facets of carboxysomes in Anabaena (Jensen and Ayala 1976). This system appears important in order to ensure that upon division, daughter cells inherit similar numbers of carboxysomes and are, therefore, not impaired in their growth (Savage et al 2010).…”

Functions, Compositions, and Evolution of the Two Types of Carboxysomes: Polyhedral Microcompartments That Facilitate CO 2 Fixation in Cyanobacteria and Some Proteobacteria

“…Microfilaments and microtubule structures have long been observed with ␤-carboxysomes (182). This interaction with the bacterial cytoskeleton resolves previous questions of how carboxysomes are apportioned to daughter cells at mitosis and is reminiscent of the partitioning systems of bacterial chromosomes, plasmids, magnetosomes, chromosomes, etc.…”

Organization, Structure, and Assembly of α-Carboxysomes Determined by Electron Cryotomography of Intact Cells

“…Carboxysome-associated tubular filaments were reported previously in cells of the cyanobacterium Anabaena 35. Tubular filaments were previously described in electron microscopy of thin sections of Salmonella enterica when a homolog of the carboxysome shell proteins, PduA, was overproduced 36.…”