Sequence properties of the 1,2-diacylglycerol 3-glucosyltransferase from Acholeplasma laidlawii membranes : Recognition of a large group of lipid glycosyltransferases in eubacteria and archaea

• Synthesis of the nonbilayer-prone α-monoglucosyldiacylglycerol (MGlcDAG) is crucial for bilayer packing properties and the                     lipid surface charge density in the membrane ofAcholeplasma laidlawii. The gene for the responsible, membrane-bound glucosyltransferase (alMGS) (EC 2.4.1.157) was sequenced and functionally cloned in Escherichia coli, yielding MGlcDAG in the recombinants. Similar amino acid sequences were encoded in the genomes of several Gram-positive                     bacteria (especially pathogens), thermophiles, archaea, and a few eukaryotes. All of these contained the typical EX7E catalytic motif of the CAZy family 4 of α-glycosyltransferases. The synthesis of MGlcDAG by a close sequence analog from                      Streptococcus pneumoniae (spMGS) was verified by polymerase chain reaction cloning, corroborating a connection between sequence and functional similarity                     for these proteins. However, alMGS and  spMGS varied in dependence on anionic phospholipid activators phosphatidylglycerol                     and cardiolipin, suggesting certain regulatory differences. Fold predictions strongly indicated a similarity for alMGS (and                     spMGS) with the two-domain structure of the E. coli MurG cell envelope glycosyltransferase and several amphipathic membrane-binding segments in various proteins. On the basis                     of this structure, the alMGS sequence charge distribution, and anionic phospholipid dependence, a model for the bilayer surface                     binding and activity is proposed for this regulatory enzyme.

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NATURVETENSKAP  -- Biologi -- Biokemi och molekylärbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Biochemistry and Molecular Biology (hsv//eng)

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