Putative Acyltransferase (AT), Left-handed parallel beta-Helix (LbH) domain; This group is composed of mostly uncharacterized proteins containing an N-terminal helical subdomain followed by a LbH domain. The alignment contains 6 turns, each containing three imperfect tandem repeats of a hexapeptide repeat motif (X-[STAV]-X-[LIV]-[GAED]-X). Proteins containing hexapeptide repeats are often enzymes showing acyltransferase activity. A few members are identified as NeuD, a sialic acid (Sia) O-acetyltransferase that is required for Sia synthesis and surface polysaccharide sialylation.
Comment:Based on the trimer structures of some members of the superfamily including E. coli Maltose O-acetyltransferase, Chlamydia Trachomatis Lpxd, and E. coli serine acetyltransferase.
Comment:Most characterized members of the LbH superfamily form trimeric structures in their active form. However, there are a few members that form different quaternary structures such as Glucose-1-phosphate adenylyltransferase which forms a tetramer. Hence, not all members may form trimers.
Jiyao W et al.(2023). "The conserved domain database in 2023.",