Molecular modelling of Androglobin

Experimental methods fail to express in vitro the full length of Androglobin (Adgb). Predominantly due to its size, the chimeric protein spans 1667 residues. Distinct from other members of this protein superfamily because of its circularly permutated heme domain, and N- terminal calpain domain, and an IQ binding motif. Here we will explore the molecular structure of Adgb. This will be achieved by first exposing the sequence to disorder prediction algorithms with the aims of identifying intrinsically disordered regions (IDRs), that may not only add noise when subjecting the sequence to fold recognition techniques. These IDRs may also be in close proximity to key molecular recognition features (MoRFs). Secondary structure prediction will not only be used to establish a common frame of reference between disorder prediction and fold recognition result, but it will also be integral to identifying the sites for potential MoRFs. Fold recognition techniques, when exposed to a query sequence, will produce tertiary structures homologous to the query sequence with known molecular functions. The structural information produced will be essential in building a complete computational model of Adgb, in hopes of guiding efforts to express in vitro the full length of the sequence. Disorder prediction revealed 5 ordered regions, of which the pre-heme sequence harboured 3; of these 2 displaying homology to calpain domains IIa and III through profile-profile alignments using Clustal Omega (Sievers et al., 2011) and a consensus formed by fold recognition techniques. Profile-profile alignments have also yielded 2 potential EF hand motifs, required for the calpain domain’s proteolytic activity. The presence of an even number of EF hands suggests that Adgb may indeed function as a monomer. In the post-heme region of the sequence 2 ordered regions have been found.