Structural characterization of a putative diguanylate cyclase conserved in hyperthermophiles

Area of Science:

• Biochemistry
• Structural Biology
• Microbiology

Background:

• Bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) is a crucial bacterial second messenger.
• Diguanylate cyclases (DGCs) synthesize c-di-GMP, often featuring a conserved GGDEF domain.
• Many putative DGCs, particularly in hyperthermophiles, remain structurally uncharacterized.

Purpose of the Study:

• To elucidate the structure and oligomerization of the hypothetical DGC Tm0107 from *Thermotoga maritima*.
• To provide structural insights into a conserved class of bacterial signaling proteins.

Main Methods:

• X-ray crystallography was used to determine the structure of the GGDEF-like domain of Tm0107.
• Analytical gel filtration was employed to measure the Stokes radii and infer solution behavior.
• Structural comparisons were made with known GGDEF domain proteins.

Main Results:

• The crystal structure of the Tm0107 GGDEF-like domain was solved at 2.1 Å resolution.
• The GGDEF-like domain exists as a monomer in solution but coordinates zinc ions at the dimer interface.
• A homodimer model for full-length Tm0107, including its coiled-coil region, was proposed, distinct from other DGCs.

Conclusions:

• Tm0107 represents a novel structural class of DGCs, forming homodimers differently than previously characterized proteins.
• The findings offer valuable structural data for conserved putative DGCs in hyperthermophilic bacteria.
• This work contributes to understanding c-di-GMP signaling regulation in extreme environments.