Molecular mechanism of photoactivation of a light-regulated adenylate cyclase.
Proc Natl Acad Sci U S A
; 114(32): 8562-8567, 2017 08 08.
Article
em En
| MEDLINE
| ID: mdl-28739908
ABSTRACT
The photoactivated adenylate cyclase (PAC) from the photosynthetic cyanobacterium Oscillatoria acuminata (OaPAC) detects light through a flavin chromophore within the N-terminal BLUF domain. BLUF domains have been found in a number of different light-activated proteins, but with different relative orientations. The two BLUF domains of OaPAC are found in close contact with each other, forming a coiled coil at their interface. Crystallization does not impede the activity switching of the enzyme, but flash cooling the crystals to cryogenic temperatures prevents the signature spectral changes that occur on photoactivation/deactivation. High-resolution crystallographic analysis of OaPAC in the fully activated state has been achieved by cryocooling the crystals immediately after light exposure. Comparison of the isomorphous light- and dark-state structures shows that the active site undergoes minimal changes, yet enzyme activity may increase up to 50-fold, depending on conditions. The OaPAC models will assist the development of simple, direct means to raise the cyclic AMP levels of living cells by light, and other tools for optogenetics.
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MEDLINE
Assunto principal:
Adenilil Ciclases
Idioma:
En
Ano de publicação:
2017
Tipo de documento:
Article