Expression of two genes of unknown function, Staphylococcus aureus scdA and Neisseria gonorrhoeae dnrN, is induced by exposure to oxidative or nitrosative stress. We show that DnrN and ScdA are di-iron proteins that protect their hosts from damage caused by exposure to nitric oxide and to hydrogen peroxide. Loss of FNR-dependent activation of aniA expression and NsrR-dependent repression of norB and dnrN expression on exposure to NO was restored in the gonococcal parent strain but not in a dnrN mutant, suggesting that DnrN is necessary for the repair of NO damage to the gonococcal transcription factors, FNR and NsrR. Restoration of aconitase activity destroyed by exposure of S. aureus to NO or H 2 O 2 required a functional scdA gene. Electron paramagnetic resonance spectra of recombinant ScdA purified from Escherichia coli confirmed the presence of a di-iron center. The recombinant scdA plasmid, but not recombinant plasmids encoding the complete Escherichia coli sufABCDSE or iscRSUAhscBAfdx operons, complemented repair defects of an E. coli ytfE mutant. Analysis of the protein sequence database revealed the importance of the two proteins based on the widespread distribution of highly conserved homologues in both gram-positive and gram-negative bacteria that are human pathogens. We provide in vivo and in vitro evidence that Fe-S clusters damaged by exposure to NO and H 2 O 2 can be repaired by this new protein family, for which we propose the name repair of iron centers, or RIC, proteins.

To investigate the e¡ects of body size and water temperature on feeding and growth in the sea cucumber Apostichopus japonicus (Selenka), the maximum rate of food consumption in terms of energy (C maxe ; J day À1 ) and the speci¢c growth rate in terms of energy (SGRe; % day À1 ) in animals of three body sizes (mean AE SE)^large (134.0 AE 3.5 g), medium (73.6 AE 2.2 g) and small (36.5 AE 1.2 g)^were determined at water temperatures of 10, 15, 20, 25 and 30 1C. Maximum rate of food consumption in terms of energy increased and SGRe decreased with increasing body weight at 10, 15 and 20 1C. This trend, however, was not apparent at 25 and 30 1C, which could be in£uenced by aestivation. High water temperatures (above 20 1C) were disadvantageous to feeding and growth of this animal; SGRe of A. japonicus during aestivation was negative. The optimum temperatures for food consumption and for growth were similar and were between 14 and 15 1C, and body size seemed to have a slight e¡ect on the optimal temperature for food consumption or growth. Because aestivation of A. japonicus was temperature dependent, the present paper also documented the threshold temperatures to aestivation as indicated by feeding cessation. Deduced from daily food consumption of individuals, the threshold temperature to aestivation for large and medium animals (73.3^139.3 g) was 24.5 À25.5 1C, while that for small animals (28.94 0.7 g) was between 25.5 and 30.5 1C. These values are higher than previous reports; di¡erences in sign of aestivation, experimental condition and dwelling district of test animals could be the reasons.

Histone crotonylation is a new lysine acylation type of post-translational modification (PTM) enriched at active gene promoters and potential enhancers in yeast and mammalian cells. However, lysine crotonylation in nonhistone proteins and plant cells has not yet been studied. In the present study, we performed a global crotonylation proteome analysis of Nicotiana tabacum (tobacco) using high-resolution LC-MS/MS coupled with highly sensitive immune-affinity purification. A total of 2044 lysine modification sites distributed on 637 proteins were identified, representing the most abundant lysine acylation proteome reported in the plant kingdom. Similar to lysine acetylation and succinylation in plants, lysine crotonylation was related to multiple metabolism pathways, such as carbon metabolism, the citrate cycle, glycolysis, and the biosynthesis of amino acids. Importantly, 72 proteins participated in multiple processes of photosynthesis, and most of the enzymes involved in chlorophyll synthesis were modified through crotonylation. Numerous crotonylated proteins were implicated in the biosynthesis, folding, and degradation of proteins through the ubiquitin-proteasome system. Several crotonylated proteins related to chromatin organization are also discussed here. These data represent the first report of a global crotonylation proteome and provide a promising starting point for further functional research of crotonylation in nonhistone proteins.