Molecular adaptation of a leaf-eating bird: stomach lysozyme of the hoatzin.
This report describes a lysozyme expressed at high levels in the stomach of the hoatzin, the only known foregut-fermenting bird. Evolutionary comparison places it among the calcium-binding lysozymes rather than among the conventional types. Conventional lysozymes were recruited as digestive enzymes twice in the evolution of mammalian foregut fermenters, and these independently recruited lysozymes share convergent structural changes attributed to selective pressures in the stomach. Biochemical convergence and parallel amino acid replacements are observed in the hoatzin stomach lysozyme even though it has a different genetic origin from the mammalian examples and has undergone more than 300 million years of independent evolution.
Kornegay
J R
JR
Department of Molecular and Cell Biology, University of California, Berkeley 94720.
Schilling
J W
JW
Wilson
A C
AC
D000222:Adaptation, Physiological / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001717:Birds / Q000235:genetics / Q000502:physiology*; D010856:Columbidae / Q000235:genetics; D004247:DNA / Q000737:chemistry / Q000235:genetics; D017931:DNA Primers; D004032:Diet; D015870:Gene Expression; D006801:Humans; D008322:Mammals / Q000235:genetics; D008969:Molecular Sequence Data; D009113:Muramidase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D018515:Plant Leaves; D016133:Polymerase Chain Reaction; D011531:Proventriculus / Q000201:enzymology*; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D004247:DNA; D009113:Muramidase