InterPro: IPR003451 LytB protein

Terpenes are among the largest groups of natural products and include compounds such as vitamins, cholesterol and carotenoids. The biosynthesis of all terpenoids begins with one or both of the two C5 precursors of the pathway: isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). In animals, fungi, and certain bacteria, the synthesis of IPP and DMAPP occurs via the well-known mevalonate pathway, however, a second, nonmevalonate terpenoid pathway has been identified in many eubacteria, algae and the chloroplasts of higher plants [1].

LytB(IspH) catalyses the conversion of 1-hydroy-2-methyl-2-(E)-butenyl 4-diphosphate into IPP and DMAPP in this second pathway The enzyme appears to be responsible for a branch-step in the nonmevalonate pathway, in that IPP and DMAPP are produced in parallel from a single precursor although the exact mechanism of this is not currently fully understood [2]. Escherichia coli LytB protein had been found to regulate the activity of RelA (guanosine 3',5'-bispyrophosphate synthetase I), which in turn controls the level of a regulatory metabolite. It is involved in penicillin tolerance and the stringent response [3].