Alejo E. Romero-Herrera

Amino Acid Sequence Evidence on the Phylogeny of Primates and Other Eutherians

The biomolecular approach to systematic and evolutionary biology is in a state of transition. Laboratories that had been determining the amino acid sequences of proteins are now caught up by the excitement of the new recombinant DNA gene cloning and sequencing technology. The possibilities for advancing knowledge in systematic and evolutionary biology by application of this new technology seem almost boundless. It is obvious that knowing the actual nucleotide sequences of genes, rather than having to infer them from the amino acid sequences of encoded proteins, allows more accurate data to be used in figuring out the genealogic relationships of organisms (see Hewett-Emmett et al., this volume, Chapter 9; also Scott and Smith, this volume, Chapter 8). During the transition, while laboratories engaged in studying molecular evolution are retooling in order to engage in nucleotide sequencing, it is worth preparing for the impending flood of these gene sequence data by taking stock of what has already been learned about phylogeny from the substantial body of amino acid sequence data. With that objective in mind, this chapter focuses attention on the phylogeny of the order Primates, both on the subbranching within the order and on the genealogic position of Primates within the subclass Eutheria as well as on the broader pattern of vertebrate branching. We will concentrate on these groups because more species are represented in them by amino acid sequence data than in any other eukaryotic branch.

An exceptional amino acid replacement on the distal side of the iron atom in proboscidean myoglobin

SummaryAmino acid sequence determination of elephant myoglobin revealed the presence of the unusual substitution E7 His → Gln. Stereochemical analyses suggest that the most suitable residue which can functionally substitute for His at this position in vertebrate globins is Gln. Physiochemical studies imply that the slower rate of autooxidation of elephant myoglobin is the result of this substitution which may confer some selective advantage on the species. Comparative sequence data of paenungulate myoglobins suggest that the His → Gln mutation probably occurred in an ancestor of Elephantinae.

The Amino Acid Sequence of Elephant (Elephas maximus) Myoglobin and the Phylogeny of Proboscidea

The complete amino acid sequence of skeletal myoglobin from the Asian elephant (Elephas maximus) is reported. The functional significance of variations seen when this sequence is compared with that of sperm whale myoglobin is explored in the light of the crystallographic model available for the latter molecule. The phylogenetic implications of the elephant myoglobin amino acid sequence are evaluated by using the maximum parsimony technique. A similar analysis is also presented which incorporates all of the proteins sequenced from the elephant. These results are discussed with respect to current views on proboscidean phylogeny.

The amino acid sequence of alligator (Alligator mississippiensis) myoglobin. Phylogenetic implications.

The amino acid sequence of myoglobin from cardiac muscle of the American alligator (Alligator mississippiensis) was established by alignment of overlapping peptides and dansyl-Edman degradation. The chain initiating methonine seems to be retained. Thus, this molecule has 154 amino acid residues rather than 153 as in other tetrapod myoglobins. Maximum parsimony analysis indicated that alligator myoglobin diverges more from both bird and mammal myoglobins than these latter do from each other. The phylogenetic implications are discussed with respect to a possible diphyletic origin for diapsid reptiles.

The myoglobin of primates X.

The amino acid sequences of skeletal muscle myoglobins from two old-world monkeys, Presbytis entellus and Erythrocebus patas, as well as one new-world monkey, Cebus apella wer inferred by homology of the tryptic and peptic peptides with the known sequence of human myoglobin and by selective dansyl-Edman degradation. These new sequences were examined phylogentically in conjunction with the 15 primate sequences already reported. It is clear that myoglobin evolution has been extremely conservative among cercopithecoid primates, so much so that the two surviving subfamilies cannot be distinguished using this protein.

Characterization of the myoglobin of the lampreyPetromyzon marinus

SummaryMyoglobin has been identified in the myocardium of the lampreyPetromyzon marinus, one of the most primitive of all vertebrates. This protein was isolated by ammonium sulphate fractionation and purified by successive chromatography on Ultrogel AcA 54, DEAE-Sephadex and CM-23 cellulose. The molecule differs substantially from the monomeric hemoglobins found in the lamprey as evidenced by its elution profile on DEAE-Sephadex and the fingerprint pattern of its enzymically-produced peptides. The functional significance of this protein in Agnatha is discussed.

Tropomyosin from adult human skeletal muscle is partially phosphorylated

Alpha and beta tropomyosins were isolated from postmortem adult human psoas and pectoralis major muscles. 31P nuclear magnetic resonance and amino acid analysis were used to show that 10% of the major alpha tropomyosin component was phosphorylated. The 31P NMR spectra also suggested that human beta tropomyosin was phosphorylated, but to a lesser extent.

Electron microscopy supports a fibrous substructure for lens intermediate filaments

The substructure of intermediate filaments from bovine lens cortical fiber cells was investigated by electron microscopy. Native filaments and synthetic ones regenerated from the total cytoskeletal extract and from the three purified subunits were examined. The morphologies from these various sources were essentially identical, with the exception that filaments reconstituted from one of the purified polypeptides were much shorter, very contorted and showed strings of aggregated protein. The solid cylindrical, unbranching filaments consisted of a helical arrangement of at least two, 5 nm diameter strands. The evidence indicated that each strand was composed of two, 2 nm diameter protofilaments which were also helically constructed (right-handed) with a periodicity of 11.6 nm. Intermediate filament diameter varied widely (8-14.8 nm, average 11.3 nm) and in a direct, linear manner relative to the apparent progression (helical) angle of the strands across the filaments face. These conclusions were obtained from observations on negatively stained intact filaments and reconstituted 4.4 nm fibrils and on positively stained transverse sections of fixed and embedded filaments.