Caister Academic Press

SM1: a Cold-loving Archaeon with Powerful Nano-grappling Hooks

Christine Moissl-Eichinger, Ruth Henneberger and Robert Huber
from: Extremophiles: Microbiology and Biotechnology (Edited by: Roberto Paul Anitori). Caister Academic Press, U.K. (2012)


The SM1 euryarchaeon represents an extraordinary microorganism: in the surface waters of cold, sulfidic springs, it lives together with filamentous bacteria, forming the so called string-of-pearls community. In the subsurface however, it can grow partner-independently as a "monospecies" biofilm. Even though the SM1 euryarchaeon is still uncultivated in the laboratory, it is accessible via an in situ cultivation technique using its own biotope as a natural chemostat. This approach allowed the study of its biology, and enabled the discovery of unique cell surface appendices with unexpected and unusually high complexity. Each of the archaeal cells is surrounded by approximately 100 protein filaments that are up to 3 micrometres long and show a high resemblance to barbwire with a tripartite grappling hook at their tip. Based on this structure the appendices were called "hami" (lat. hamus = (grappling) hook). These hami represent perfectly evolved, natural mechanical nano-tools that could find applications in the growing field of nanobiotechnology read more ...
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