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Identification of the first Oomycete annexin as a (1→3)‐β‐ d ‐glucan synthase activator
Author(s) -
Bouzenzana Jamel,
Pelosi Ludovic,
Briolay Anne,
Briolay Jérôme,
Bulone Vincent
Publication year - 2006
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2006.05389.x
Subject(s) - biology , biochemistry , activator (genetics) , atp synthase , oomycete , biosynthesis , enzyme , gene
Summary (1→3)‐β‐ d ‐Glucans are major components of the cell walls of Oomycetes and as such they play an essential role in the morphogenesis and growth of these microorganisms. Despite the biological importance of (1→3)‐β‐ d ‐glucans, their mechanisms of biosynthesis are poorly understood. Previous studies on (1→3)‐β‐ d ‐glucan synthases from Saprolegnia monoica have shown that three protein bands of an apparent molecular weight of 34, 48 and 50 kDa co‐purify with enzyme activity. However, none of the corresponding proteins have been identified. Here we have identified, purified, sequenced and characterized a protein from the 34 kDa band and clearly shown that it has all the biochemical properties of proteins from the annexin family. In addition, we have unequivocally demonstrated that the purified protein is an activator of (1→3)‐β‐ d ‐glucan synthase. This represents a new type of function for proteins belonging to the annexin family. Two other proteins from the 48 and 50 kDa bands were identified as ATP synthase subunits, which most likely arise from contaminations by mitochondria during membrane preparation. The results, which are discussed in relation with the possible regulation mechanisms of (1→3)‐β‐ d ‐glucan synthases, represent a first step towards a better understanding of cell wall polysaccharide biosynthesis in Oomycetes.