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RESEARCH ARTICLE Open Access Evolutionary patterns of proteinase activity in

Summary: RESEARCH ARTICLE Open Access
Evolutionary patterns of proteinase activity in
attine ant fungus gardens
Tatyana A Semenova1,2,3
, David P Hughes1,4
, Jacobus J Boomsma1
, Morten Schiøtt1*
Background: Attine ants live in symbiosis with a basidiomycetous fungus that they rear on a substrate of plant
material. This indirect herbivory implies that the symbiosis is likely to be nitrogen deprived, so that specific
mechanisms may have evolved to enhance protein availability. We therefore hypothesized that fungal proteinase
activity may have been under selection for efficiency and that different classes of proteinases might be involved.
Results: We determined proteinase activity profiles across a wide pH range for fungus gardens of 14 Panamanian
species of fungus-growing ants, representing eight genera. We mapped these activity profiles on an independently
obtained molecular phylogeny of the symbionts and show that total proteinase activity in lower attine symbionts
peaks at ca. pH 6. The higher attine symbionts that have no known free-living relatives had much higher
proteinase activities than the lower attine symbionts. Their total in vitro proteinase activity peaked at pH values
around 5, which is close to the pH that the ants maintain in their fungus gardens, suggesting that the pH
optimum of fungal proteinases may have changed after the irreversible domestication of evolutionary more
derived fungal symbionts. This notion is also supported by buffering capacities of fungus gardens at pH 5.2 being


Source: Andrews, Anne M. - Huck Institutes of the Life Sciences, Pennsylvania State University


Collections: Biology and Medicine