Subunit heterogeneity in arthropod hemocyanins: I. Chelicerata

Markl, Jürgen; Markl, A.; Schartau, Walter; Linzen, Bernt

doi:10.1007/bf00689845

Cited by 83 publications

(43 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The open reading frames translate into polypeptides of 624 to 631 amino acids with calculated molecular masses ranging from 71.5 to 72.4 kDa (Table I). This corresponds well with the apparent molecular mass of 67-76 kDa (17). In total, the 24-mer hemocyanin acquires a total molecular mass of 1,726,459 Da.…”

Section: Resultssupporting

confidence: 77%

Complete Sequence of the 24-mer Hemocyanin of the TarantulaEurypelma californicum

Voit

Feldmaier-Fuchs²,

Schweikardt

et al. 2000

Journal of Biological Chemistry

View full text Add to dashboard Cite

Hemocyanins are large oligomeric respiratory proteins found in many arthropods and molluscs. The hemocyanin of the tarantula Eurypelma californicum is a 24-mer protein complex with molecular mass of 1,726,459 Da that consists of seven different polypeptides (a-g), each occupying a distinct position within the native molecule. Here we report the complete molecular structure of the E. californicum hemocyanin as deduced from the corresponding cDNAs. This represents the first complex arthropod hemocyanin to be completely sequenced. The different subunits display 52-66% amino acid sequence identity. Within the subunits, the central domain, which bears the active center with the copper-binding sites A and B, displays the highest degree of identity. Using a homology modeling approach, the putative three-dimensional structure of individual subunits was deduced and compared. Phylogenetic analyses suggest that differentiation of the individual subunits occurred 400 -550 million years ago. The hemocyanin of the stemline Chelicerata was probably a hexamer built up of six distinct subunit types a, b/c, d, e, f, and g, whereas that of the early Arachnida was originally a 24-mer that emerged after the differentiation of subunits b and c.

show abstract

Section: Resultssupporting

confidence: 77%

Complete Sequence of the 24-mer Hemocyanin of the TarantulaEurypelma californicum

Voit

Feldmaier-Fuchs²,

Schweikardt

et al. 2000

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…Contingency of subunit loss on physiology is supported by the observation that many derived spider species have lost most hemocyanin subunits and/or undergone duplications of remaining paralogs (e.g., the g paralogs of Cupiennius salei; absence of hemocyanin in Dysdera sp. [30,31]) Accordingly, biochemical assays have not identified hemocyanins in Pycnogonida, Solifugae, or Acariformes ( [26,27,60]). We note that hemocyanins are also not observed in the genomes of the mite Tetranychus urticae (Acariformes) or the tick Ixodes scapularis (Parasitiformes).…”

Section: Incidence Of Hemocyanins In Apulmonate Cheliceratesmentioning

confidence: 99%

Cross-bracing uncalibrated nodes in molecular dating improves congruence of fossil and molecular age estimates

Sharma

Wheeler

2014

Front Zool

View full text Add to dashboard Cite

Introduction: The practice of molecular dating is an essential tool for hypothesis testing in evolutionary biology. Vagaries of fossilization and taphonomic bias commonly engender high uncertainty in molecular dating in taxonomic groups wherein few fossils can be unambiguously assigned to phylogenetic nodes. A recent and novel implementation in molecular dating, "cross-bracing", exploits gene duplications by formally linking calibrated node dates throughout the paralogous subtrees through hierarchical Bayesian models. An unexplored refinement of this method is cross-bracing nodes with unknown dates, in addition to calibrated nodes, such that all nodes representing the same cladogenetic events have linked priors. We applied such a refinement to molecular dating in chelicerates, one of the earliest groups of arthropods present in the fossil record, but whose molecular dating has been greatly inconsistent in the literature. We inferred divergence times using hemocyanin paralogs isolated from de novo assembled transcriptomic libraries, and multiple fossil calibrations. Results: We show that extending cross-bracing to uncalibrated nodes greatly reduced variance in estimates of divergence times throughout the phylogeny, particularly for estimated diversification ages of spiders and scorpions, whereas cross-bracing calibrated nodes alone did not affect age estimation for uncalibrated, derived clades. Comparing ages inferred with extended cross-bracing to the fossil record, we observe smaller gaps between diversification and the first appearance of crown group fossils than have previously been inferred, particularly for spiders. Our dating indicates that scorpions have a Silurian origin, but diversification of extant lineages occurred near the Triassic-Jurassic boundary, falsifying previous inference of Permian diversification age based on extant distribution alone. Conclusion: The significant reduction of variance in divergence time estimates upon extending cross-bracing to uncalibrated nodes makes this approach greatly suited for evolutionary inference in groups with poor fossil records, with particular reference to terrestrial arthropods.

show abstract

“…The second major peak that elutes at 16 S has a 280 nm:340 nm ratio of Ͼ20 (Fig. 1B), indicating a protein that does not bind oxygen by a copper complex and that has therefore been referred to as non-respiratory protein (NRP) (14) However, to avoid possible confusion with chelicerate NRPs that are not related to hemocyanin (26), the H. americanus NRP has been renamed PHc here.…”

Section: Purification and Analysis Of Phc-mentioning

confidence: 99%

Identification, Molecular Cloning, and Phylogenetic Analysis of a Non-respiratory Pseudo-hemocyanin of Homarus americanus

Burmester

1999

Journal of Biological Chemistry

View full text Add to dashboard Cite

Copper-containing hemocyanins serve to transport oxygen in many arthropod species. Here I describe the identification and cDNA cloning of a structurally closely related non-respiratory pseudo-hemocyanin (PHc) of the American lobster, Homarus americanus. This protein has lost the ability to bind copper and, therefore, oxygen because a histidine residue in copper-binding site A is replaced by tyrosine. Like many arthropod hemocyanins, PHc forms a hexamer. It consists of two different subunit types of 660 and 661 amino acids, respectively, that share a 94.4% sequence identity. Whereas Homarus hemocyanin is produced in the hepatopancreas, PHc is synthesized by the ovaries and the heart tissue. Because different levels of PHc were observed in distinct individuals, I propose an association of the synthesis of this protein with the molting or reproduction cycle, similar to the hexamerins, insect storage proteins that are also related to the hemocyanins. However, phylogenetic analyses show that PHc derived independently from crustacean hemocyanins. Therefore, Homarus PHc is a member of a new class within the growing hemocyanin protein superfamily.

show abstract

Subunit heterogeneity in arthropod hemocyanins: I. Chelicerata

Cited by 83 publications

References 14 publications

Complete Sequence of the 24-mer Hemocyanin of the TarantulaEurypelma californicum

Complete Sequence of the 24-mer Hemocyanin of the TarantulaEurypelma californicum

Cross-bracing uncalibrated nodes in molecular dating improves congruence of fossil and molecular age estimates

Identification, Molecular Cloning, and Phylogenetic Analysis of a Non-respiratory Pseudo-hemocyanin of Homarus americanus

Contact Info

Product

Resources

About