PASTA in penicillin binding proteins and serine/threonine kinases: a recipe of structural, dynamic and binding properties

Penicillin binding proteins (PBPs) and Serine Threonine kinases (STPKs) are two classes of bacterial enzymes whose involvement in a series of vital processes in bacterial growth and division is well assessed. Many components belonging to both classes share an ancillary domain named PASTA, whose functional role is not completely deciphered so far. Indeed, why PASTA motives decorate, often in multiple copies, PBPs and STPKs is yet an unanswered question. At present, PASTA is annotated as a sensor domain. It has been proposed that its binding to opportune ligands, i.e. muropeptides, is able to activate the cognate proteins to their functions. However, some experimental data proved that such role might not be a general property of PASTA. Furthermore, many PASTA modules, recognized in bacterial genomes, are not associated with either PBPs or STPKs enzymes. Thus, which is the function and/or if there is a context-dependent function of PASTA modules is still an open question. Here we present a survey of the structural, binding and dynamic properties so far described for PASTA domains. We also propose a possible criterion to discriminate between PASTA modules of STPKs or PBPs solely based on their sequences.