A quantitative approach relating emergent features of complex traits to protein expression

Abstract

Linking complex, multigenic traits to protein activity is an important challenge in current biology, including applications in the medical sciences, agriculture, or forestry. Two simple algorithms are presented here to establish that link. The first one describes synergistic interactions of n proteins in shaping a complex trait ('weak emergence') as opposed to a simply additive 'modular' contribution of these proteins. A coefficient κ is defined that allows to quantify the degree of emergent interaction. For cases of strong emergence a separate formalism is introduced, implying that a number of n proteins at concentrations exceeding individual threshold values are required to spontaneously form a new, complex trait. Threshold concentrations are allowed to vary, depending on the concentrations of the other constitutive proteins. The experimental effort is estimated to provide a corresponding database for applying both formalisms, including high-throughput phenomics, and manipulation of protein concentrations using the molecular toolbox. Future efforts will be directed to overcome current limitations of the models that ignore the dynamics of protein-trait relationships with time, and the importance of the spatial arrangement of proteins for emergent interaction.

Keywords: Control coefficient; Multigenic traits; Strong emergence; Systems biology; Weak emergence.