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PERYPLAZMATYCZNE B-GLUKANY
BAKTERII GRAM-UJEMNYCH
Iwona Komaniecka, Adam Choma
Zakład Mikrobiologii Ogólnej, Instytut Mikrobiologii i Biotechnologii,
Uniwersytet Marii Curie-Skłodowskiej,
ul. Akademicka 19, 20-033 Lublin,
e-mail: ikoma@biotop.umcs.lublin.pl
Wpłynęło w marcu 2006 r.
1. Wprowadzenie. 2. Struktura peryplazmatycznych glukanów. 2.1. Liniowe b-(1,2)-glukany. 2.2. Cykliczne b-(1,2)-glukany (cyklosoforany). 2.3. Cykliczne b-(1,2)-glukany z jednym wiązaniem typu a-(1,6) w pierścieniu. 2.4. Cykliczne b-(1,3);(1,6)-glukany. 3. Synteza peryplazmatycznych glukanów. 3.1. Biosynteza szkieletu cukrowego. 3.2. Modyfikacja oligosacharydów. 3.3. Regulacja biosyntezy OPG. 4. Rola peryplazmatycznych glukanów. 5. Podsumowanie.
Periplasmic b-glucans of Gram-negative bacteria
Abstract: Osmoregulated Periplasmic Glucans (OPGs) are intrinsic components of the bacterial envelope of many Proteobacteria. These oligosaccharides share several common structural characteristics: D-glucose is the sole component sugar, b-glycosidic bonds are the main type of linkages, glucans synthesis and accumulation are inversely proportional to the osmotic strength of the environment.
Four families of periplasmic beta-glucans have been described so far: 1) linear oligosaccharides, which are branched and contain b-(1,2) and b-(1,6) linkages; 2) cyclic b-(1,2) glucans; 3) cyclic b-(1,2) glucans with one a-(1,6) linkage; 4) cyclic b-(1,3); b-(l,6) glucans. OPGs may be substituted by one or several residues such as: sn-1-phosphoglycerol, phosphoethanolamine or phospho-choline, which originate from the membrane phospholipids. Also some intermediary metabolites can serve as glucan substituents (i.e.: acetic, methylmalonic and succinic acid O-ester). Periplasmic b-glucans may be neutral or anionic in character. Except for the role in osmoprotection, OPGs are important in virulence, symbiosis, biofilm formation and resistance to antibiotics.
1. Introduction. 2. The structure of periplasmic glucans. 2.1. Linear b-(1,2)-glucans. 2.2. Cyclic b-(1,2)-glucans (cyclosophorans). 2.3. Cyclic b-(1,2)-glucans with one a-(1,6)-linkage in the ring. 2.4. Cyclic b-(1,3);(1,6)-glucans. 3. Synthesis of periplasmic glucans. 3.1. Biosynthesis of sugar backbone. 3.2. Modification of oligosaccharides. 3.3. Regulation of OPG biosynthesis. 4. The role of periplasmic glucans. 5. Summary.
Słowa kluczowe: osmoregulacja, OPG, peryplazmatyczny b-glukan
Key words: osmoregulation, OPG, periplasmic b-glucan
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