A Hemoglobin with an Optical Function

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A. H. Jay Burr, Peter Hunt, Donna R. Wagar, Sylvia Dewilde, Mark L. Blaxter, Jacques R. Vanfletereni, and Luc Moens. A Hemoglobin with an Optical Function. Journal of Biological Chemistry, 275 (7), 2000. 4810-4815.

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Hemoglobins are best known as oxygen transport pro-teins. Here we describe a hemoglobin from the parasitic nematode Mermis nigrescens (Mn-GLB-E) that has an optical, light shadowing function. The protein accumu-lates to high concentration as intracellular crystals in the ocellus of mature phototactic adult females while also being expressed at low concentration in other tis-sues. It differs in sequence and expression pattern from Mn-GLB-B, a second Mermis globin. It retains the struc-ture and oxygen-binding and light-absorbing properties typical of nematode hemoglobins. As such, recruitment to a shadowing role in the eye appears to have occurred by changes in expression without modification of bio-chemistry. Both globins are coded by genes interrupted by two introns at the conserved positions B12.2 and G7.0, which is in agreement with the 3exon/2intron pat-tern model of globin gene evolution.

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NATO International Collaborative Grant
National Science and Engineering Research Council of Canada (NSERC)
Leverhulme Trust
Fund for Scientific Research Flanders (FWO)