Globin-folded proteins are present in a wide range of life forms and crucial in a variety of physiological processes. Here, we characterize globin 33 (GLB-33) of Caenorhabditis elegans, a soil dwelling nematode. The
glb-33 gene encodes a globin domain which is preceded by a G-protein coupled receptor domain (GPCR), making it the longest of all the C. elegans globins [1]. GLB-33 is expressed in sensory, inter- and motor neurons possibly linking sensory input with the animal's locomotion [1]. GLB-33's presence in the ALN and PLN neuron pairs hints at oxygen sensing. This hypothesis is strengthened by the biochemistry of the globin domain, which appears to have features of a typical O2 sensor with high O2 affinity, next to a fast nitrite reductase activity [2]. At present, the neuropeptide ligand of the GPCR still needs to be identified, but its similarity with the FMRFamide receptor of another nematode (Ascaris suum) is apparent [2]. Both ligands are likely influencing the conformation of the entire molecule, making it difficult to predict any biological effect purely based on biochemical information. Therefore the study of the protein's function needs an integrated approach, ranging from biochemical to physiological techniques. Preliminary experiments have indicated that GLB-33 is not required for survival and fecundity under normal or induced oxidative stress conditions. However animals lacking GLB-33 have a slower recovery rate after a 24-h oxygen deprivation period.[1] Hoogewijs D., Geuens E., Dewilde S., Vierstraete A., Moens L., Vinogradov S. & Vanfleteren J.R. (2007) BMC Genomics, 8:356[2] Tilleman L., Germani F., De Henau S., Helbo S., Desmet F., Berghmans H., Van Doorslaer S., Hoogewijs D., Schoofs L., Braeckman B.P., Moens L., Fago A. & Dewilde S. (2015) The Journal of Biological Chemistry.