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CHARAKTERYSTYKA
LIPOPOLISACHARYDOW
RHIZOBIUM
I
ICH ZNACZENIE
W PROCESIE
SYMBIOZY
Anna
Turska-Szewczuk, Ryszard Russa
Artykuł
dedykowany prof., dr hab. Krystynie Kotełko, jest zmodyfikowaną formą wykładu wygłoszonego 26 października
2004 na Sesji Naukowej pt. „Badania immunochemiczne
endotoksyn (LPS) bakterii", podczas uroczystości poświęconej
pamięci prof., dr hab. Krystyny Kotełko, na Wydziale Biologii i Ochrony Środowiska
Uniwersytetu Łódzkiego
1. Wstęp.
2. Ogólna charakterystyka lipopolisacharydu. 3. Kontrola
genetyczna syntezy LPS. 4. Budowa i biosynteza lipidu A. 5. Struktura
oligosacharydu rdzeniowego. 5.1. Znaczenie regionu
rdzeniowego w symbiozie. 6. Część
0-swoista. 6.1. Biosynteza polisacharydu 0-swoistego.
7. Rola lipopolisacharydu
Rhizobium w symbiozie. 7.1. Symbiotyczne właściwości
mutantów Rhizobium o zmienionym LPS. 7.2. Cechy mutantów lipopolisacharydowych. 7.3. Zmiany
w LPS podczas symbiozy. 8. Podsumowanie
The
characterization of the Rhizobium lipopolysaccharides and
their significance in symbiosis
Abstract: Four types of rhizobial polysaccharides i.e. exopolysaccharides (EPSs),
cyclic -glucans, K antigens, and
Lipopolysaccharides (LPSs), have been shown by mutation studies to be required
in the development
of various root nodule symbioses. This chapter deals with LPS, a
major constituent of the bacterial outer
membrane which plays a crucial, albeit poorly understood role in
nodule invasion in the symbiotic process.
Mutations that affect LPS structure indicate that
normal abundance and certain structural features of the LPS
O-specific polysaccharide are required for successful infection of
host leguminous plants. Consequences of abnormal O antigen deficiency
include the induction of host defence responses, from early blocks in infection thread formation to defects in infection
thread release, severely reduced proliferation of
bacteroids and finally stunted nodule development. The LPS also
plays an important role in adapting bacteria to the plant and
other environments. Its structure is altered during biosynthesis
in response to factors such as low pH, low oxygen, and host
anthocyanins. The more hydrophobic character of LPS occurred
during the differentiation from bacterium to bacteroid and is due
to higher proportion of long chain fatty
acids attached to the lipid A moiety, shortening of PS O-chain and alterations in the composition of 0 antigen
including an increase in acetylation and methylation pattern of the saccharidic domains. Interestingly, these changes are
similar to those exhibited by some pathogenic
bacteria on infection of their hosts.
Currently,
no information is available on the molecular mechanisms in the
symbiont triggering these alterations.
1. Introduction.
2. The general characterization of the lipopolysaccharide. 3. Genetics
of LPS synthesis. 4. The structure and biosynthesis of lipid A moiety. 5. The
structure of core oligosaccharide. 5.1. The significance of core region in symbiosis. 6. The O-specific polysaccharide. 6.1. Biosynthesis of O-specific polysaccharide. 7. The implication of Rhizobium
LPS in symbiosis. 7.1. Symbiotic properties of Rhizobium mutants with altered LPS. 7.2. Characteristics
of lipopolysaccharide mutants. 7.3. Changes of LPS in symbiotic state. 8. Conclusion
Uniwersytet
Marii Curie-Skłodowskiej
Zakład Mikrobiologii Ogólnej
Ul. Akademicka 19, 20-033 Lublin
Wpłynęło
w lutym 2004 r.
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