Evolutionary activation of acidic chitinase in herbivores through the H128R mutation in ruminant livestock

Eri Tabata; Ikuto Kobayashi; Takuya Morikawa; Akinori Kashimura; Peter O Bauer; Fumitaka Oyama

doi:10.1016/j.isci.2023.107254

Evolutionary activation of acidic chitinase in herbivores through the H128R mutation in ruminant livestock

iScience. 2023 Jul 3;26(8):107254. doi: 10.1016/j.isci.2023.107254. eCollection 2023 Aug 18.

Authors

Eri Tabata^{1

2}, Ikuto Kobayashi¹, Takuya Morikawa¹, Akinori Kashimura¹, Peter O Bauer³, Fumitaka Oyama¹

Affiliations

¹ Department of Chemistry and Life Science, Kogakuin University, Hachioji, Tokyo 192-0015, Japan.
² Research Fellow of Japan Society for the Promotion of Science (PD), Koujimachi, Chiyoda-ku, Tokyo 102-0083, Japan.
³ Bioinova a.s., Videnska 1083, 142 00 Prague, Czech Republic.

Abstract

Placental mammals' ancestors were insectivores, suggesting that modern mammals may have inherited the ability to digest insects. Acidic chitinase (Chia) is a crucial enzyme hydrolyzing significant component of insects' exoskeleton in many species. On the other hand, herbivorous animal groups, such as cattle, have extremely low chitinase activity compared to omnivorous species, e.g., mice. The low activity of cattle Chia has been attributed to R128H mutation. The presence of either of these amino acids correlates with the feeding behavior of different bovid species with R and H determining the high and low enzymatic activity, respectively. Evolutionary analysis indicated that selective constraints were relaxed in 67 herbivorous Chia in Cetartiodactyla. Despite searching for another Chia paralog that could compensate for the reduced chitinase activity, no active paralogs were found in this order. Herbivorous animals' Chia underwent genetic alterations and evolved into a molecule with low activity due to the chitin-free diet.

Keywords: Evolutionary biology; Molecular biology; Zoology.