The chaperonin HSP60 (GroEL) proteins are essential
in eubacterial genomes and in eukaryotic organelles. Functional
regions inferred from mutation studies and the Escherichia
coli GroEL 3D crystal complexes are evaluated in a
multiple alignment across 43 diverse HSP60 sequences, centering
on ATP/ADP and Mg2+ binding sites, on residues
interacting with substrate, on GroES contact positions,
on interface regions between monomers and domains, and
on residues important in allosteric conformational changes.
The most evolutionary conserved residues relate to the
ATP/ADP and Mg2+ binding sites. Hydrophobic
residues that contribute in substrate binding are also
significantly conserved. A large number of charged residues
line the central cavity of the GroEL–GroES complex
in the substrate-releasing conformation. These span statistically
significant intra- and inter-monomer three-dimensional
(3D) charge clusters that are highly conserved among sequences
and presumably play an important role interacting with
the substrate. Unaligned short segments between blocks
of alignment are generally exposed at the outside wall
of the Anfinsen cage complex. The multiple alignment reveals
regions of divergence common to specific evolutionary groups.
For example, rickettsial sequences diverge in the ATP/ADP
binding domain and Gram-positive sequences diverge in the
allosteric transition domain. The evolutionary information
of the multiple alignment proffers attractive sites for
mutational studies.