Bacterial cell wall polysaccharides kssd

Introduction-Cell wall and functions
Gram +ve and -ve cell wall
Bacterial cell wall - structure
Peptidoglycan-Composition and Structure
Types of polysaccharidesBacterial cell wall
Functions of polysaccharides in Bacterial cell wall

1. Bacterial Cell Wall Polysaccharides Shan Sujatha

2. Introduction CELL WALL The cell wall is the outer most layer of the cell. In many cases the cell wall comes in direct contact with the environment. Function Protection of the cell . Maintains the shapes of the cell. Maintains the osmotic integrity of the cell   Assist some cells in attaching to other cells or in eluding antimicrobial drugs . Providing attachment sites for bacteriophages. Play an essential role in cell division

3. Gram Positive Cell wall • Usually thick, homogenous, composed mainly of peptidoglycan. • It accounts for 50-90% of the dry weight of the cell wall. • Contain large amount of teichoic acids (polymers of glycerol or ribitol joined by phosphate group ). Special components of Gram positive cell wall is Teichoic acid • Teichoic acids are connected to either peptidoglycan or to plasma membrane lipids. • Absent in gram negative bacteria. Functions of Teichoic Acid: . Antigenic determinant (receptor molecule for bacteriophages). . Participate in the supply of Mg to the cell by binding Mg++ . Regulate normal cell division Gram Negative Cell Wall • Multi layered and more complex than Gram positive cell walls. • Peptidoglycan of gram negative bacteria is thin and comprises only 10% or less of cell wall.

4. Types of Polysaccharides in bacterial cell wall 1. Bacterial Glycoproteins are lipopolysaccharides (LPSs) and capsular antigens which are attached by lipid anchors (lipid A or diacylglycerophosphates ) in gram-negative bacteria 2. Membrane-Derived Oligosaccharides -e also known as the osmoregulated periplasmic glucans (OPGs) --MDOs are a heterogeneous family of closely related, highly branched oligosaccharides containing glucose as the sole sugar. They are substituted with sn-1- phosphoglycerol , phosphoethanolamine , and 0-succinyl ester residues

5. 3.Lipopolysaccharide -made up of a lipid and a polysaccharide which are joined together by a covalent bond.In Gm – ve bacteria-Lipopolysaccharide (LPS) comprises of three parts: (i) “O” antigen, (ii) core polysaccharide, and (iii) lipid A . The sugars commonly present are heptose and 3-deoxy-D-mannooctulosonic acid 4. Lipo oligosaccharides - glycolipids which are present in the outer membrane of certain types of gram-negative bacteria. 5. Capsular Polysaccharide - The capsular polysaccharide constitutes the outermost layer of the bacterial cell and mediates its direct interaction with the environment Accessory polysaccharides consists of Sugars like teichoic acid(Glycerol or Ribitol ), Rhamnose,Glucose,Galactose or mannose

6. Functions Of Polysaccharides in Bacterial cell wall Importance of Glycosylation The N- or O-glycosylation of the peptide in bacteria could induce the host response by causing infection Lipopolysaccharides--act as a candidate target for new antimicrobial agents. LPS generally acts as endotoxin as it binds to the cell receptor (CD14/TLR4/MD2) complex in monocytes, dendritic cells, macrophages, and B cells, which thereby promotes the secretion of proinflammatory cytokines, nitric oxide, and eicosanoids Capsular Polysaccharide The capsular polysaccharide constitutes the outermost layer of the bacterial cell and mediates its direct interaction with the environment

7. Thank You By S.Sujathak7