PMID- 33067191 OWN - NLM STAT- MEDLINE VI - 87 IP - 1 TI - Tyrosine Nitration of Flagellins: a Response of Sinorhizobium meliloti to Nitrosative Stress. CI - Copyright © 2020 American Society for Microbiology. LA - eng PT - Journal Article PT - Research Support, Non-U.S. Gov't PL - United States TA - Appl Environ Microbiol JT - Applied and environmental microbiology JID - 7605801 IS - 1098-5336 (Electronic) LID - e02210-20 [pii] LID - 10.1128/AEM.02210-20 [doi] FAU - Cazalé, Anne-Claire AU - Cazalé AC AUID- ORCID: 0000-0002-6822-7186 AD - LIPM, Université de Toulouse, INRAE, CNRS, INSA, Castanet-Tolosan, France anne-claire.cazale-noel@inrae.fr. FAU - Blanquet, Pauline AU - Blanquet P AD - LIPM, Université de Toulouse, INRAE, CNRS, INSA, Castanet-Tolosan, France. FAU - Henry, Céline AU - Henry C AD - PAPPSO, Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France. FAU - Pouzet, Cécile AU - Pouzet C AD - FR3450, Université de Toulouse, CNRS, UPS, Plateforme d'imagerie, Castanet-Tolosan, France. FAU - Bruand, Claude AU - Bruand C AD - LIPM, Université de Toulouse, INRAE, CNRS, INSA, Castanet-Tolosan, France. FAU - Meilhoc, Eliane AU - Meilhoc E AD - LIPM, Université de Toulouse, INRAE, CNRS, INSA, Castanet-Tolosan, France. IS - 0099-2240 (Linking) RN - 12777-81-0 (Flagellin) RN - 31C4KY9ESH (Nitric Oxide) RN - 42HK56048U (Tyrosine) SB - IM MH - Flagellin/*metabolism MH - Nitric Oxide/metabolism MH - *Nitrosative Stress MH - Sinorhizobium meliloti/*metabolism MH - Tyrosine/*metabolism OTO - NOTNLM OT - *Rhizobium OT - *flagella OT - *mass spectrometry (MS) OT - *nitric oxide OT - *nitrotyrosine OT - *posttranslational modification (PTM) PMC - PMC7755255 DCOM- 20210322 LR - 20210618 DP - 20201217 DEP - 20201217 AB - Rhizobia are bacteria which can either live as free organisms in the soil or interact with plants of the legume family with, as a result, the formation of root organs called nodules in which differentiated endosymbiotic bacteria fix atmospheric nitrogen to the plant's benefit. In both lifestyles, rhizobia are exposed to nitric oxide (NO) which can be perceived as a signaling or toxic molecule. NO can act at the transcriptional level but can also modify proteins by S-nitrosylation of cysteine or nitration of tyrosine residues. However, only a few molecular targets of NO have been described in bacteria and none of them have been characterized in rhizobia. Here, we examined tyrosine nitration of Sinorhizobium meliloti proteins induced by NO. We found three tyrosine-nitrated proteins in S. meliloti grown under free-living conditions, in response to an NO donor. Two nitroproteins were identified by mass spectrometry and correspond to flagellins A and B. We showed that one of the nitratable tyrosines is essential to flagellin function in motility.IMPORTANCE Rhizobia are found as free-living bacteria in the soil or in interaction with plants and are exposed to nitric oxide (NO) in both environments. NO is known to have many effects on animals, plants, and bacteria where only a few molecular targets of NO have been described so far. We identified flagellin A and B by mass spectrometry as tyrosine-nitrated proteins in Sinorhizobium meliloti in vivo We also showed that one of the nitratable tyrosines is essential to flagellin function in motility. The results enhanced our understanding of NO effects on rhizobia. Identification of bacterial flagellin nitration opens a new possible role of NO in plant-microbe interactions.