Protein controls formation of biominerals

Essential component of biomineralization discovered in marine fumes

Astrosclera willeyana © University of Göttingen
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Scientists have been able to identify an important genetic component in the process of biomineralization, the biological formation of inorganic materials by organisms: they were able to isolate a protein from the marine sponge Astroclera willeyana, which controls biomineral formation as an enzyme. Close relatives of this enzyme are involved in numerous basic metabolic processes in other organisms.

In their study, the scientists started from the question whether the ability to biomineralize in multicellular animals, so-called Metazoa, has a common origin or originated independently of different animal strains. According to the geobiologists in the online edition of "Science", the investigations now show that at least part of the biomineralization apparatus goes back to the last common ancestor of the Metazoa.

Biominerals can form stable materials, such as skeletons and snails or solid reef structures in the ocean, and play important roles in marine ecosystems. Such mineralized hard parts frequently occurred in the geological history of about 550 to 520 million years ago in the late Precambrian to early Cambrian. Their existence is preceded by unicellular organisms that secrete large quantities of lime. The genetic control mechanisms by which living cells excrete mineralized structures have been largely unknown to date, as have their evolutionary origins.

"Living Fossil" as a research object

The investigations, the scientists around junior professor Gert Wörheide from the University of Göttingen together with colleagues from Brisbane / Australia were carried out on the "living fossil" Astrosclera willeyana. These sponges were instrumental in reef-building processes during early epochs of geology.

"Because sponges are historically at the base of the family tree of multicellular animals and thus close to the common ancestor of Metazoa, they are ideal for decoding original biomineralization processes, " explains Wörheide. The team of scientists chose a new research approach. Her so-called palaeogenomic works are based on genetic techniques and protein expression as well as phylogenetic reconstructions. display

Reactive enzyme isolated

The researchers isolated from A. willeyana the particularly reactive enzyme astrosclerine. This new enzyme of the alpha carbonic anhydrase family is an essential component of the genetic building block in the process of biomineralization. Close relatives of this family of enzymes are involved in many basic metabolic processes. The gene responsible for the production of astrosclerin must have been present in the last common ancestor of the Metazoa, as the phylogenetic analyzes show.

"As a single copy, this important gene has subsequently been duplicated independently in swarms and other animals. This laid the foundations for the variety of physiological processes in which the enzyme is involved today, "says Gttinger geobiologist. According to W rheide, the materials resulting from biomineralisation are important as new materials and in biotechnological applications.

(idw - University G ttingen, 15.06.2007 - DLO)