Room 2-262/264
Phone:
(+49) 6131 - 392 -4477 (office) -3437
(lab)
Fax: (+49) 6131 - 392 -4652
Email: burmeste(AT)uni-mainz.de
Deutsche
VersionEvolution and Function of Respiratory Proteins
Life on
earth emerged under anoxic conditions and oxygen was originally a toxic
agent. With
the rise of atmospheric oxygen during the Proterozoic period, the
respiratory
chain evolved that uses O2 as an electron acceptor for
ATP-production. First metazoan animals were small and probably simple
diffusion
was sufficient for O2 supply. In the late Precambrium
period, however,
animals commenced to increase in size and thus required the formation
of
efficient respiratory organs, circulatory systems and oxygen-transport
and
–storage proteins. Using modern molecular, biochemical, cell biological
and bioinformatical techniques, we are
investigating the evolutionary history and the
present roles of the arthropod
hemocyanins, the insect hemoglobins,
and the vertebrate neuroglobins and
cytoglobins.
The Evolution of the Arthropod Hemocyanin Superfamily
Hemocyanins are large multimeric
(n x
6)
copper-containing proteins that deliver oxygen via the hemolymph of
many
arthropod species. They have been investigated in detail in the
Chelicerata and
the Crustacea, whereas data from other arthropod taxa are sparse. We
have
identified and sequenced for the first time hemocyanins from the
diplopod and
chilopod Myriapoda. Hemocyanins are also present in the Onychophora,
suggesting
that respiratory proteins emerged before the radiation of the
Panarthropoda. The
superfamily of arthropod hemocyanins includes in addition to the
proteins for
which they are named, the arthropod phenoloxidases, certain crustacean
and
insect storage proteins (pseudohemocyanins and hexamerins), as well as
the
highly diverged hexamerin receptors of the insects. We are
investigating the functional changes that led to the diversification of
the arthropod hemocyanin superfamily.
The Role of
Intracellular Hemoglobins
in Insect Respiration
The
aerobic metabolism of
large animals requires a sufficient supply of oxygen to the internal
tissues.
Gas-exchange in insects and many other terrestrial arthropods is
mediated via
trachea. For this reason, specialised O2-transport or
storage
proteins have been regarded unnecessary in most insects. However, the
fruitfly Drosophila melanogaster and other insects
possess intracellular hemoglobins. This observation suggests that
oxygen supply in insects may be more
complex than previously thought and may depend on globin-mediated
transport in
addition to diffusion. Our research interests focuss on the possible function of the
insect
hemoglobins in insect metabolism and respiration (Cooperation
with T. Hankeln, Institute of Molecular Genetics, Mainz).
Globins
are respiratory proteins that occur in all
kingdoms of organisms. Among the vertebrates, hemoglobin serves for the
transport of oxygen in the blood, myoglobin supplies oxygen to the
mitochondria
of the muscle cells. We recently identified two novel vertebrate globin
types
that we termed neuroglobin (Ngb) and cytoglobin (Cygb). Ngb is an
intracellular, monomeric globin of
17 kDa that
is preferentially
expressed in the nerve cells of the central and peripheral nervous
system, and
also in endocrine tissues. High Ngb concentrations are present in the
neuronal retina. Ngb most likely supplies oxygen to these
metabolically active cells. Ngb has been analysed from various mammals
and
fishes. The
human NGB gene is located on
chromosome 14q24 and displays a unique exon-intron structure. Ngb is
highly conserved among vertebrates: Mouse and human Ngb share 94%
of the amino acids. Ngb is most likely homologous to the invertebrate
nerve-specific globins, but
displays only limited amino acid sequence similarity
to the known vertebrate myoglobins (< 21% identity) or hemoglobins
(< 25%
identity). Phylogenetic
analysis shows that the Ngb represents a distinct protein family that
diverged
from the other globins early in animal evolution, probably before the
Protostomia-Deuterostomia
split. Recombinant
Ngb
has an intermediate oxygen
affinity of about 1 Torr. Unlike in most globins, the iron atom in Ngb
is
hexacoordinated in the deoxy-form. Cygb has been
identified in mouse, man,
rat, Xenopus and zebrafish. Mammalian Cygb is unusual because it has 20
amino
acid extensions at their N- and C-termini. Cygb is mainly expressed in
fibroblasts and related cell types, but its function is still uncertain (Cooperation
with T. Hankeln, Institute of Molecular Genetics, Mainz).
Dr.
Mark Haberkamp (Postdoc): Functional analysis of neuroglobin in
vivo and in vitro
Dr. Silke Hagner-Holler (PhD student): Molecular characterisation
and evolution of arthropod hemocyanins
Marc
Schmidt (PhD student): Expression analysis of neuroglobin and
cytoglobin in mammlian tissues
Anja Rösner (PhD student): Hypoxia response and globin expression
in fish
Stephanie Mitz (PhD student): Functional analysis of cytoglobin in vivo
and in vitro
Joachim Storf (Diploma student): Molecular cloning, expression and
functional analysis of insect
hemoglobins
Anke Bentmann (Diploma student): Neuroglobin in the mammalian visual
system
Dominik Kugelstadt (Diploma student): Neuroglobin and cytoglobin in
chicken
Lectures and Courses
Sequenzforschung
und Genomanalyse (V, WiSe)
Allgemeine Zoologie
II, Teil B: Vegetative Physiologie (V, SoSe)
Zoologische Übungen für Anfänger (Ü, WiSe)
Tierphysiologische Übungen für Anfänger (Ü, WiSe, SoSe)
FI-Übungen "Molekulare Zellbiologie" (Ü, WiSe)
FI-Übungen "Struktur, Funktion und Evolution von Proteinen" im Rahmen des Fernstudiums (Ü, WiSe)
FII-Übungen "Molekulare Tierphysiologie" (Ü, WiSe, SoSe)