biostudies-literatureSong JYNIGMS NIH HHS10780-5https://www.ebi.ac.uk/biostudies/studies/S-EPMC3127908biostudies-literatureUnknown108(26)Positive phototaxis systems have been well studied in bacteria; however, the photoreceptor(s) and their downstream signaling components that are responsible for negative phototaxis are poorly understood. Negative phototaxis sensory systems are important for cyanobacteria, oxygenic photosynthetic organisms that must contend with reactive oxygen species generated by an abundance of pigment photosensitizers. The unicellular cyanobacterium Synechocystis sp. PCC6803 exhibits type IV pilus-dependent negative phototaxis in response to unidirectional UV-A illumination. Using a reverse genetic approach, together with biochemical, molecular genetic, and RNA expression profiling analyses, we show that the cyanobacteriochrome locus (slr1212/uirS) of Synechocystis and two adjacent response regulator loProceedings of the National Academy of Sciences of the United States of AmericaNear-UV cyanobacteriochrome signaling system elicits negative phototaxis in the cyanobacterium Synechocystis sp. PCC 6803.PMC3127908R01 GM068552GM068552R01 GM068552-07S1R01 GM068552-08R01 GM068552-07Cho HSLagarias JCCho JISong JYPark YIJeon JSfalseNear-UV cyanobacteriochrome signaling system elicits negative phototaxis in the cyanobacterium Synechocystis sp. PCC 6803.Positive phototaxis systems have been well studied in bacteria; however, the photoreceptor(s) and their downstream signaling components that are responsible for negative phototaxis are poorly understood. Negative phototaxis sensory systems are important for cyanobacteria, oxygenic photosynthetic organisms that must contend with reactive oxygen species generated by an abundance of pigment photosensitizers. The unicellular cyanobacterium Synechocystis sp. PCC6803 exhibits type IV pilus-dependent negative phototaxis in response to unidirectional UV-A illumination. Using a reverse genetic approach, together with biochemical, molecular genetic, and RNA expression profiling analyses, we show that the cyanobacteriochrome locus (slr1212/uirS) of Synechocystis and two adjacent response regulator lo2011-01-01T00:00:00Z2011 Jun2025-04-05T10:02:45.732Z2019-03-27T03:06:33ZS-EPMC31279082167028410.1073/pnas.1104242108