Structures of the PelD cyclic diguanylate effector involved in pellicle formation in Pseudomonas aeruginosa PAO1.
The second messenger bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) plays a vital role in the global regulation in bacteria. Here, we describe structural and biochemical characterization of a novel c-di-GMP effector PelD that is critical to the formation of pellicles by Pseudomonas aeruginosa. We present high-resolution structures of a cytosolic fragment of PelD in apo form and its complex with c-di-GMP. The structure contains a bi-domain architecture composed of a GAF domain (commonly found in cyclic nucleotide receptors) and a GGDEF domain (found in c-di-GMP synthesizing enzymes), with the latter binding to one molecule of c-di-GMP. The GGDEF domain has a degenerate active site but a conserved allosteric site (I-site), which we show binds c-di-GMP with a K(d) of 0.5 μm. We identified a series of residues that are crucial for c-di-GMP binding, and confirmed the roles of these residues through biochemical characterization of site-specific variants. The structures of PelD represent a novel class of c-di-GMP effector and expand the knowledge of scaffolds that mediate c-di-GMP recognition.
Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Zhi
Z
Li
Jui-Hui
JH
Chen
Yue
Y
Hao
Satish K
SK
Nair
D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002473:Cell Wall / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011550:Pseudomonas aeruginosa / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D002352:Carrier Proteins; C062025:bis(3',5')-cyclic diguanylic acid; D006152:Cyclic GMP