Figure A. Methyl
phosphate. B. Methyl phosphonate. Phosphonate compounds are characterised
by a direct link
between carbon (C) and phosphorus (P), marked with red. C. The molecular
structure of the
C-P lyase complex (Figure: Ditlev E. Brodersen, Aarhus University)
(August 18, 2015) Bacteria
exhibit extreme adaptability, which makes them capable of surviving in the most
inhospitable conditions. New research results produced by Danish and British
researchers now reveal the molecular details behind one of the secret weapons
used by bacteria in their battle to survive under very nutrient-poor and even
toxic conditions.
All living things need phosphate to grow, which is why
several hundred million tons of phosphate fertilisers are used every year in
agriculture throughout the world. The nutrient content is so low in many parts
of the world’s oceans that all growth comes to a halt, and bacteria have
therefore developed advanced mechanisms to extract phosphate from other
substances. These are known as phosphonate compounds, which are produced by
many primitive organisms and account for the largest known stock of phosphorus
in the marine environment (see figure). Many of these compounds are formed as
toxins (antibiotics) as part of the ongoing battle for survival among marine
organisms. Several million kilograms of glyphosate (Roundup®) are used as
pesticide in agriculture every year, and the accumulation of residues of this phosphonate
compound in groundwater has led to growing concern in recent years.
Bacteria capable of converting phosphonate compounds into
phosphate to boost their growth have developed an arsenal of fourteen proteins
for this purpose, approximately half of which are enzymes required for the
chemical transformation of the substances. Five of these enzymes accumulate in
the cells in a large complex called the C-P lyase complex, which can catalyse
two of the total of five reactions required to use the phosphonate compound for
growth.
An international team consisting of researchers from both
the Department of Molecular Biology and Genetics, Aarhus University, and the
Medical Research Council (MRC) in Cambridge, UK, have now determined the
precise molecular structure of the C-P lyase complex, making it possible for
the first time to understand how the secret weapon used by bacteria actually
works. Using X-ray crystallography and electron microscopy, the researchers
were able to achieve extremely detailed insight into the structure of four of
the enzymes, as well as the location of the fifth enzyme in the complex.