Blood Lines for Blood Protein Run Deep

© James Newhouse, Maqsudul Alam

Proteins possibly used for oxygen sensing in primitive organisms appear to be hemoglobin ancestors. Microbiologist Maqsudul Alam at the University of Hawaii and collaborators at the University of Texas (UT) Southwestern Medical Center at Dallas found a "protoglobin," a hemoglobin progenitor, in Aeropyrum pernix, an aerobic organism that lives in near-boiling salt water. They also found the protoglobin in Methanosarcina acetivorans, an anaerobe found in lake-bottom muck, decaying leaves, and the human gut.

Phylogenetic analysis pointed toward archaebacteria as housing such predecessors, Alam explains. Using an algorithm to search microbial genomic databases, he found candidate genes in the two organisms. The research provides potentially important information on M. acetivorans, says David Graham, a biochemist at UT, Austin. He notes that the organism has a number of enzymes to protect it from oxygen's toxic effects. "The heme-based sensor described here could be...