Background: 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 PBPs and STPKs show linked an ancillary domain
named PASTA, whose functional role is not completely deciphered so far. It has been proposed
that PASTAs are sensor modules that by binding opportune ligands (i.e. muropeptides) activate
the cognate proteins to their functions. However, based on recent data, the sensor annotation
sounds true for PASTA from STPKs, and false for PASTA from PBPs.
Objective: Different PASTA domains, belonging or not to different protein classes, sharing or not
appreciable sequence identities, always show identical folds. This survey of the structural, binding
and dynamic properties of PASTA domains pursues the reasons why identical topologies may turn
in different roles.
Results: Amino acid compositions, total charges and distribution of the hydrophobic/hydrophilic
patches on the surface, significantly vary among PASTAs from STPKs and PBPs and appear to
correlate with different functions. A possible criterion to discriminate between PASTA modules of
STPKs or PBPs solely based on their sequences is proposed. Possibly reflecting different species
as well as functional roles and evolutionary profile, our routine represents a fast even though approximate
method to distinguish between PASTA belonging to different classes.