Changes in wall teichoic acid during the rod-sphere transition of Bacillus subtilis 168

129

SUMMARY Humans have been increasingly recognized as being superorganisms, living in close contact with a microbiota on all their mucosal surfaces. However, most studies on the human microbiota have focused on gaining comprehensive insights into the composition of the microbiota under different health conditions (e.g., enterotypes), while there is also a need for detailed knowledge of the different molecules that mediate interactions with the host. Glycoconjugates are an interesting class of molecules for detailed studies, as they form a strain-specific barcode on the surface of bacteria, mediating specific interactions with the host. Strikingly, most glycoconjugates are synthesized by similar biosynthesis mechanisms. Bacteria can produce their major glycoconjugates by using a sequential or an en bloc mechanism, with both mechanistic options coexisting in many species for different macromolecules. In this review, these common themes are conceptualized and illustrated for all major classes of known bacterial glycoconjugates, with a special focus on the rather recently emergent field of glycosylated proteins. We describe the biosynthesis and importance of glycoconjugates in both pathogenic and beneficial bacteria and in both Gram-positive and -negative organisms. The focus lies on microorganisms important for human physiology. In addition, the potential for a better knowledge of bacterial glycoconjugates in the emerging field of glycoengineering and other perspectives is discussed.

Section: Fig 6 O-antigen Lps Biosynthesis and Lps Assembly And Transpmentioning

confidence: 78%

The Sweet Tooth of Bacteria: Common Themes in Bacterial Glycoconjugates

Tytgat

Lebeer

2014

129

“…2B) (32,133,393). The degree of ␣-D-glucosylation is 0.8, but this has been shown to depend on the age of the cells and the P i concentration in the growth medium (68,190).…”

Section: Structures Of Wta and Ltamentioning

confidence: 99%

“…Growth of a tagF1 (rodC1) strain with a defect in the Gro-P transferase TagF (Fig. 4) (399) at this temperature gave WTA with chains approximately 8 units long, in contrast to chain lengths of approximately 53 residues when the strain was grown at the permissive temperature (393). This strain contained only 16% of its WTA when grown at the restrictive temperature.…”

Section: Mutants Defective In Lta and Wta Assemblymentioning

confidence: 99%

A Continuum of Anionic Charge: Structures and Functions ofd-Alanyl-Teichoic Acids in Gram-Positive Bacteria

Neuhaus

Baddiley

2003

907

1,097

SUMMARY Teichoic acids (TAs) are major wall and membrane components of most gram-positive bacteria. With few exceptions, they are polymers of glycerol-phosphate or ribitol-phosphate to which are attached glycosyl and d-alanyl ester residues. Wall TA is attached to peptidoglycan via a linkage unit, whereas lipoteichoic acid is attached to glycolipid intercalated in the membrane. Together with peptidoglycan, these polymers make up a polyanionic matrix that functions in (i) cation homeostasis; (ii) trafficking of ions, nutrients, proteins, and antibiotics; (iii) regulation of autolysins; and (iv) presentation of envelope proteins. The esterification of TAs with d-alanyl esters provides a means of modulating the net anionic charge, determining the cationic binding capacity, and displaying cations in the wall. This review addresses the structures and functions of d-alanyl-TAs, the d-alanylation system encoded by the dlt operon, and the roles of TAs in cell growth. The importance of dlt in the physiology of many organisms is illustrated by the variety of mutant phenotypes. In addition, advances in our understanding of d-alanyl ester function in virulence and host-mediated responses have been made possible through targeted mutagenesis of dlt. Studies of the mechanism of d-alanylation have identified two potential targets of antibacterial action and provided possible screening reactions for designing novel agents targeted to d-alanyl-TA synthesis.

“…After translocation across the cytoplasmic membrane, the TA is covalently linked to PG. One of the enzymes involved in the precursor synthesis, TagF, is essential in B. subtilis, and thermosensitive mutants display a spherical phenotype (149)(150)(151). Two other enzymes, TagG and TagH, are thought to act together as a translocase for the lipid-linked TA precursor (105).…”

Section: Localization Of Other Proteins Involved In Bacterial Cellmentioning

confidence: 99%

Bacterial Cell Wall Synthesis: New Insights from Localization Studies

Scheffers

Pinho

2005

539

489

SUMMARY In order to maintain shape and withstand intracellular pressure, most bacteria are surrounded by a cell wall that consists mainly of the cross-linked polymer peptidoglycan (PG). The importance of PG for the maintenance of bacterial cell shape is underscored by the fact that, for various bacteria, several mutations affecting PG synthesis are associated with cell shape defects. In recent years, the application of fluorescence microscopy to the field of PG synthesis has led to an enormous increase in data on the relationship between cell wall synthesis and bacterial cell shape. First, a novel staining method enabled the visualization of PG precursor incorporation in live cells. Second, penicillin-binding proteins (PBPs), which mediate the final stages of PG synthesis, have been localized in various model organisms by means of immunofluorescence microscopy or green fluorescent protein fusions. In this review, we integrate the knowledge on the last stages of PG synthesis obtained in previous studies with the new data available on localization of PG synthesis and PBPs, in both rod-shaped and coccoid cells. We discuss a model in which, at least for a subset of PBPs, the presence of substrate is a major factor in determining PBP localization.