This domain is present in cGMP-specific phosphodiesterases, adenylyl and guanylyl cyclases, phytochromes, FhlA and NifA. Adenylyl and guanylyl cyclases catalyse ATP and GTP to the second messengers cAMP and cGMP, respectively, these products up-regul ...
This domain is present in cGMP-specific phosphodiesterases, adenylyl and guanylyl cyclases, phytochromes, FhlA and NifA. Adenylyl and guanylyl cyclases catalyse ATP and GTP to the second messengers cAMP and cGMP, respectively, these products up-regulating catalytic activity by binding to the regulatory GAF domain(s). The opposite hydrolysis reaction is catalysed by phosphodiesterase. cGMP-dependent 3',5'-cyclic phosphodiesterase catalyses the conversion of guanosine 3',5'-cyclic phosphate to guanosine 5'-phosphate. Here too, cGMP regulates catalytic activity by GAF-domain binding. Phytochromes are regulatory photoreceptors in plants and bacteria which exist in two thermally-stable states that are reversibly inter-convertible by light: the Pr state absorbs maximally in the red region of the spectrum, while the Pfr state absorbs maximally in the far-red region. This domain is also found in FhlA (formate hydrogen lyase transcriptional activator) and NifA, a transcriptional activator which is required for activation of most Nif operons which are directly involved in nitrogen fixation. NifA interacts with sigma-54. This domain can bind biliverdine and phycocyanobilin (Matilla et al., FEMS Microbiology Reviews, fuab043, 45, 2021, 1. https://doi.org/10.1093/femsre/fuab043).
The GAF domain is named after some of the proteins it is found in, including cGMP-specific phosphodiesterases, adenylyl cyclases and FhlA. It is also found in guanylyl cyclases and phytochromes [1,2]. The structure of a GAF domain shows that the doma ...
The GAF domain is named after some of the proteins it is found in, including cGMP-specific phosphodiesterases, adenylyl cyclases and FhlA. It is also found in guanylyl cyclases and phytochromes [1,2]. The structure of a GAF domain shows that the domain shares a similar fold with the PAS domain [3]. This domain can bind O2, CO and NO (Matilla et.al., FEMS Microbiology Reviews, fuab043, 45, 2021, 1. https://doi.org/10.1093/femsre/fuab043).
This domain is found linked to a wide range of non-homologous domains in a variety of bacteria. It has been shown to be homologous to the adenylyl cyclase catalytic domain [1] and has diguanylate cyclase activity [4]. This observation correlates with ...
This domain is found linked to a wide range of non-homologous domains in a variety of bacteria. It has been shown to be homologous to the adenylyl cyclase catalytic domain [1] and has diguanylate cyclase activity [4]. This observation correlates with the functional information available on two GGDEF-containing proteins, namely diguanylate cyclase and phosphodiesterase A of Acetobacter xylinum, both of which regulate the turnover of cyclic diguanosine monophosphate. In the WspR protein of Pseudomonas aeruginosa, the GGDEF domain acts as a diguanylate cyclase, PDB:3bre, when the whole molecule appears to form a tetramer consisting of two symmetrically-related dimers representing a biological unit. The active site is the GGD/EF motif, buried in the structure, and the cyclic dimeric guanosine monophosphate (c-di-GMP) bind to the inhibitory-motif RxxD on the surface. The enzyme thus catalyses the cyclisation of two guanosine triphosphate (GTP) molecules to one c-di-GMP molecule [6,7,8].
