Dimer asymmetry and light activation mechanism in Brucella blue-light sensor histidine kinase

RINALDI, JIMENA; FERNÁNDEZ, IGNACIO; SHIN, HEEWHAN; SYCZ, GABRIELA; GUNAWARDANA, SEMINI; KUMARAPPERUMA, INDIKA; PAZ, JUAN; OTERO, LISANDRO H.; CERUTTI, MARÍA LAURA; ZORREGUIETA, ANGELES; REN, ZHONG; KLINKE, SEBASTIÁN; YANG, XIAOJING; GOLDBAUM, FERNANDO A.

Mbio

American Society for Microbiology

Lugar: Washington; Año: 2021 vol. 12

Theability to sense and respond to environmental cues is essential foradaptation and survival in living organisms. In bacteria, thisprocess is accomplished by multidomain sensor histidine kinases thatundergo autophosphorylation in response to specificstimuli, thereby triggering downstream signaling cascades. However,the molecular mechanism of allosteric activation is not fullyunderstood in these important sensor proteins. Here, we report thefull-length crystal structure of a blue light photoreceptor LOVhistidine kinase (LOV-HK) involved in light-dependent virulencemodulation in the pathogenic bacterium Brucella abortus. Jointanalyses of dark and light structures determined in differentsignaling states have shown that LOV-HK transitions from a symmetricdark structure to a highly asymmetric light state. The initial localand subtle structural signal originated in the chromophore-bindingLOV domain alters the dimer asymmetry via a coiled-coil rotary switchand helical bending in the helical spine. These amplifiedstructural changes result in enhanced conformational flexibilityand large-scale rearrangements that facilitate the phosphoryltransfer reaction in the HK domain.p { margin-bottom: 0.25cm; line-height: 115% }