Recombinant expression of Mus musculus myoglobin

Expression and characterization of rainbow trout Oncorhynchus mykiss recombinant myoglobin

Recombinant expression system was established for rainbow trout myoglobin (Mb) considering its unique primary structure of having one unusual deletion and two cysteine residues in contrast to the other fish Mbs. The obtained recombinant Mb without His-tag showed non-cooperative thermal denaturation profile. The presence of free cysteine residue(s) in rainbow trout Mb was demonstrated by reacting with a sulfhydryl agent, 4, 4´-dithiodipyridine, which ultimately resulted in the oxidation of Mb with characteristic changes in visible absorption spectra. Besides, the recombinant Mb displayed steady peroxidase reactivity indicating in vivo roles of Mb as a reactive oxygen species scavenger. The findings of the present study indicate that the solitary rainbow trout Mb, which ultimately manifest typical secondary structure pattern and corroborate characteristic functionality, can be over expressed in recombinant system devoid of fusion tag.

Evolution of mammalian diving capacity traced by myoglobin net surface charge

Extended breath-hold endurance enables the exploitation of the aquatic niche by numerous mammalian lineages and is accomplished by elevated body oxygen stores and adaptations that promote their economical use. However, little is known regarding the molecular and evolutionary underpinnings of the high muscle myoglobin concentration phenotype of divers. We used ancestral sequence reconstruction to trace the evolution of this oxygen-storing protein across a 130-species mammalian phylogeny and reveal an adaptive molecular signature of elevated myoglobin net surface charge in diving species that is mechanistically linked with maximal myoglobin concentration. This observation provides insights into the tempo and routes to enhanced dive capacity evolution within the ancestors of each major mammalian aquatic lineage and infers amphibious ancestries of echidnas, moles, hyraxes, and elephants, offering a fresh perspective on the evolution of this iconic respiratory pigment.

Structural stabilities of recombinant scombridae fish myoglobins

An expression system of recombinant myoglobins (Mb) of 3 scombridae fish species was constructed. The stability of these Mbs was compared with native Mbs purified from slow skeletal muscle. The addition of hemin during the cultivation of an Escherichia coli strain harboring a pGEX-2T expression vector was found to be necessary to prevent recombinant Mb from degrading and to attain its proper folding. The stabilities of recombinant Mbs were generally lower than those of native Mbs, partly due to the absence of post-translational modification. The alpha-Helical content of bullet tuna recombinant Mb at 10 degrees C was the lowest (29.0%) among the recombinant Mbs examined (the values for bluefin tuna and bigeye tuna Mbs being 34.8 and 35.5%, respectively). On the other hand, the stabilities of recombinant Mbs of bluefin tuna and bigeye tuna against denaturants (urea and guanidine hydrochloride) were found to be similar, whereas bullet tuna recombinant Mb exhibited the lowest stability among these Mbs. The pattern of temperature-dependent decrease in the alpha-helical content supported these results.