TY - JOUR

T1 - Sulfur deprivation-induced expression of THB1, a Chlamydomonas reinhardtii truncated hemoglobin, is mediated by nitrate reductase-dependent NO production

AU - Zalutskaya, Zhanneta

AU - Filina, Valentina

AU - Ermilova, Elena

PY - 2018/1/1

Y1 - 2018/1/1

N2 - During sulfur (S) deprivation, Chlamydomonas reinhardtii mediates a suite of specific responses to efficiently acquire S from various sources and remodel primary metabolism. Although the truncated hemoglobin 1 (THB1)-dependent regulation of a subset of S limitation-responsive genes has been elucidated, the mechanism through which THB1transcription is triggered in S-deprived cells is not known. Here, we show that signaling proteins and regulators associated with S deprivation specific responses did not control THB1 expression. Following S depletion, rapid increase in nitrite concentrations is essential for THB1upregulation. These changes are consistent with NO accumulation. Increased nitrite, NO and THB1mRNA levels were not observed in mutant cells without diaphorase-NR activity. Our findings suggest that nitrate reductase - nitric oxide-forming nitrite reductase system plays a positive role in THB1 transcription via generation of NO from nitrite in S-starved cells. NR-dependent NO production may be regarded as an early trigger, which contributes to Chlamydomonas adaptability to nutrient stresses.

AB - During sulfur (S) deprivation, Chlamydomonas reinhardtii mediates a suite of specific responses to efficiently acquire S from various sources and remodel primary metabolism. Although the truncated hemoglobin 1 (THB1)-dependent regulation of a subset of S limitation-responsive genes has been elucidated, the mechanism through which THB1transcription is triggered in S-deprived cells is not known. Here, we show that signaling proteins and regulators associated with S deprivation specific responses did not control THB1 expression. Following S depletion, rapid increase in nitrite concentrations is essential for THB1upregulation. These changes are consistent with NO accumulation. Increased nitrite, NO and THB1mRNA levels were not observed in mutant cells without diaphorase-NR activity. Our findings suggest that nitrate reductase - nitric oxide-forming nitrite reductase system plays a positive role in THB1 transcription via generation of NO from nitrite in S-starved cells. NR-dependent NO production may be regarded as an early trigger, which contributes to Chlamydomonas adaptability to nutrient stresses.

KW - Nitrate reductase

KW - Nitric oxide

KW - Sulfur limitation responses

KW - Truncated hemoglobin 1

UR - http://www.scopus.com/inward/record.url?scp=85052973737&partnerID=8YFLogxK

U2 - 10.21685/1680-0826-2018-12-2-4

DO - 10.21685/1680-0826-2018-12-2-4

M3 - Article

AN - SCOPUS:85052973737

VL - 12

SP - 97

EP - 108

JO - Protistology

JF - Protistology

SN - 1680-0826

IS - 2

ER -