Polyamines in bacteria: pleiotropic effects yet specific mechanisms.

Extensive data in a wide range of organisms point to the importance of polyamine homeostasis for growth. The two most common polyamines found in bacteria are putrescine and spermidine. The investigation of polyamine function in bacteria has revealed that they are involved in a number of functions other than growth, which include incorporation into the cell wall and biosynthesis of siderophores.

Polyamines are essential for the formation of plague biofilm.

We provide the first evidence for a link between polyamines and biofilm levels in Yersinia pestis, the causative agent of plague. Polyamine-deficient mutants of Y. pestis were generated with a single deletion in speA or speC and a double deletion mutant.

Identification of three critical acidic residues of poly(ADP-ribose) glycohydrolase involved in catalysis: determining the PARG catalytic domain.

PARG [poly(ADP-ribose) glycohydrolase] catalyses the hydrolysis of alpha(1''-->2') or alpha(1'''-->2'') O-glycosidic linkages of ADP-ribose polymers to produce free ADP-ribose. We investigated possible mechanistic similarities between PARG and glycosidases, which also cleave O-glycosidic linkages. Glycosidases typically utilize two acidic residues for catalysis, thus we targeted acidic residues within a conserved region of bovine PARG that has been shown to contain an inhibitor-binding site.

Crystallization, X-ray diffraction and oligomeric characterization of arginine decarboxylase from Yersinia pestis, a key polyamine biosynthetic enzyme.

Arginine decarboxylase (ADC) is a 70 kDa pyridoxal-5'-phosphate (PLP) dependent enzyme that controls an alternative step in the biosynthesis of polyamines in some bacteria and plants. Crystals of ADC were flash-cooled and diffracted to 3.0 A resolution using a synchrotron-radiation source.

Spectrophotometric and steady-state kinetic analysis of the biosynthetic arginine decarboxylase of Yersinia pestis utilizing arginine analogues as inhibitors and alternative substrates.

The PLP-dependent, biosynthetic arginine decarboxylase (ADC) of Yersinia pestis was investigated using steady-state kinetics employing structural analogues of arginine as both alternative substrates and competitive inhibitors. The inhibitor analysis indicates that binding of the carboxyl and guanidinium groups of the substrate, l-arginine, provides essentially all of the free energy change realized upon substrate binding in the ground state. Furthermore, recognition of the guanidinium group is primarily responsible for substrate specificity.

Identification of an inhibitor binding site of poly(ADP-ribose) glycohydrolase.

Polymers of ADP-ribose involved in the maintenance of genomic integrity are converted to free ADP-ribose by the action of poly(ADP-ribose) glycohydrolase (PARG). As an approach to mapping functions of PARG onto the amino acid sequence of the protein, we report here experiments that identify an amino acid residue involved in the binding of potent PARG inhibitors. A photoreactive inhibitor, [alpha-(32)P]-8-azidoadenosine diphosphate (hydroxymethyl)pyrrolidinediol (8-N(3)-ADP-HPD), was used to photolabel a recombinant bovine PARG catalytic fragment (rPARG-CF).