Sacculus

Proteins identified by their ability to bind labelled (3-lactam antibiotics in vivo and in vitro. The intrinsic activities of PBPs include transglycosylase/transpepti-dase, carboxypeptidase and endopeptidase activities required for the formation of the bacterial murein sacculus forming the bacterial cell wall. The enzymes are located in the cytoplasmic membrane. 

Also in the PP, associated with the CM, one can find the murein sacculus (for a review see [8]). This network is formed by the macromolecule pepti-doglycan, which confers the characteristic cell shape and provides the cell with mechanical protection. Peptidoglycans are unique to prokaryotic organisms and consist of a glycan backbone of N-acetylated muramic acid and N-acetylated glucosamine and cross-linked peptide chains [9-13]. 

Holtje, J. Y. (1998). Growth of the stress-bearing and shape-maintaining murein sacculus of Escherichia coli, Microbiol. Mol. Biol. Rev., 62, 181-203. 

Koch, A. L. (2000). The exoskeleton of bacterial cells (the sacculus) still a highly attractive target for antibacterial agents that will last for a long time, Crit. Rev. Microbiol., 26, 1-35. 

The sacculus is an invagination of the antennal epithelium that consists of three chambers (Itoh et al., 1991 Shanbhag et al., 1995). It contains a few more types of sensilla, some of which have no pores and are likely to contain thermohygroreceptive neurons. The sensilla that contain olfactory neurons are all of the dw category, C sensilla similar to those on the surface. Due to the relative inaccessibility of these sensilla nothing is known about their physiology. 

Itoh T., Yokohari F., TanimuraT. and Tominaga Y. (1991) External morphology of sensilla in the sacculus of an antennal flagellum of the fruit fly Drosophila melanogaster Meigen (Diptera Drosophilidae). Int. J. Insect Morphol. Embryol. 20, 235-243. 

Shanbhag S. R., Singh K. and Singh R. N. (1995) Fine structure and primary sensory projections of sensilla located in the sacculus of the antenna of Drosophila melanogaster. Cell Tissue Res. 282, 237-249. 

Cell envelopes of archaea diifer distinctly from those of bacteria and show remarkable structural and chemical diversity. Murein, the typical sacculus-forming polymer of bacteria, and lipopolysaccharide-containing outer membranes, characteristic of gramnegative bacteria, are not found in archaea. Crystalline surface layers (S-layers) are common in both prokaryotic domains and they consist of protein or glycoprotein subunits (Table 1). However, S-layers in archaea have a form-stabilizing function especially when they are the only envelope layer outside the cytoplasmic membrane, while in bacteria S-layers have no distinct form-stabilizing function. 

The gram-positive rods or cocci of the order Methanobacteriales [3] and of the genus Methanopyrus [4] possess an electron-dense cell wall sacculus, mostly 15-20 nm in width,... 

Species Rigid sacculus S-layer (sheath) Polymer... 

Fig. 1. Thin section of Methanothermus fervidus (symbols S, S-layer Ps, pseudomurein sacculus ...

Halococcus morrhuae forms single cells or cuboidal packets. The cells are surrounded by one electron-dense layer outside the cytoplasmic membrane, 50-60 nm in width (Fig. 8). This layer forms a rigid cell wall sacculus [79] and tends to become laminated as was also observed for Methanosarcina barkeri [61,64]. The rigid cell-wall sacculi prevent lysis of the cocci in media with low ionic strength and have been isolated by the usual techniques applied for gram-positive bacteria [80]. 

The lack of a murein cell-wall sacculus and the discovery of different cell-envelope polymers and structures in some physiologically unusual prokaryotes, was one of the first biochemical and cytological evidences in favour of Carl Woese s archaebacteria concept [46,149,150]. Since then, increasingly more unique cell-envelope polymers and new types of biosynthetic pathways have become known. These findings corroborate the proposal that the archaea represent a third lineage of organisms [150] in addition to bacteria and eucarya, and that the common ancestor or ancestral population of the archaea did not evolve any cell-wall polymer before it radiated into the various sublineages known today [46,151]. 

Furukawa T, Kuno M, Matsuura S (1982) Quantal analysis of a decremental response at hair cell-afferent fibre synapses in the goldfish sacculus. J Physiol (Land) 522 181-195. 

DSP toxins Dinophysis acuta, acuminate, sacculus, fortii, caudate... 

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