Table 6.

Outstanding Proline Catabolism Structural Biology Targets

Target	Significance
Eukaryotic PRODH	Cancer drug design target
PRODH complexed with ubiquinone	No structure of any PRODH or PutA complexed with a bona fide biological quinone; provides information about membrane association.
GSALDH complexed with P5C/GSAL	Addresses the question of whether GSALDH directly binds GSAL or converts P5C to GSAL in the active site
1C PutA	The most complex of all PutAs; provides insight into the structural basis of transcriptional regulation and functional switching
3B PutA dimer	Potentially unique dimer induced by ligand binding
PutA with P5C/GSAL in the tunnel	Determine the identity of the channeled species; reveal the roles of tunnel residues in facilitating channeling
PRODH-GSALDH protein–protein complex	Structural basis of PRODH-GSALDH intermolecular substrate channeling

GSAL, l-glutamate-γ-semialdehyde.