Diet and Adaptive Evolution of Alanine-Glyoxylate Aminotransferase Mitochondrial Targeting in Birds.

Adaptations to different diets represent a hallmark of animal diversity. The diets of birds are highly variable, making them an excellent model system for studying adaptive evolution driven by dietary changes. To test whether molecular adaptations to diet have occurred during the evolution of birds, we examined a dietary enzyme alanine-glyoxylate aminotransferase (AGT), which tends to target mitochondria in carnivorous mammals, peroxisomes in herbivorous mammals, and both mitochondria and peroxisomes in omnivorous mammals. A total of 31 bird species were examined in this study, which included representatives of most major avian lineages. Of these, 29 have an intact mitochondrial targeting sequence (MTS) of AGT. This finding is in stark contrast to mammals, which showed a number of independent losses of the MTS. Our cell-based functional assays revealed that the efficiency of AGT mitochondrial targeting was greatly reduced in unrelated lineages of granivorous birds, yet it tended to be high in insectivorous and carnivorous lineages. Furthermore, we found that proportions of animal tissue in avian diets were positively correlated with mitochondrial targeting efficiencies that were experimentally determined, but not with those that were computationally predicted. Adaptive evolution of AGT mitochondrial targeting in birds was further supported by the detection of positive selection on MTS regions. Our study contributes to the understanding of how diet drives molecular adaptations in animals, and suggests that caution must be taken when computationally predicting protein subcellular targeting.

Methyl 4-(5-meth-oxy-1H-indol-3-yl)benzoate.

In the title compound, C(17)H(15)NO(3), the dihedral angle between the benzene ring and the indole ring system is 22.5 (3)°. In the crystal, mol-ecules are linked by N-H⋯π and C-H⋯O inter-actions.

2-(4-Fluoro-phen-yl)quinoxaline.

In the title compound, C(14)H(9)FN(2), the dihedral angle between the benzene ring and the quinoxaline ring system is 22.2 (3)°. Any aromatic π-π stacking in the crystal must be very weak, with a minimum centroid-centroid separation of 3.995 (2) Å.

4-[4,5-Bis(pyridin-2-yl)-1H-imidazol-2-yl]phenol monohydrate.

In the title hydrate, C(19)H(14)N(4)O·H(2)O, the dihedral angle between the two pyridine rings is 38.0 (2)°. The dihedral angle between the imidazole and benzene rings is 25.3 (2)°. The crystal structure is stabilized by inter-molecular O-H⋯O, O-H⋯N and N-H⋯O hydrogen bonds.