Four-stranded mini microtubules formed by Prosthecobacter BtubAB show dynamic instability.
Proc Natl Acad Sci U S A
; 114(29): E5950-E5958, 2017 07 18.
Article
em En
| MEDLINE
| ID: mdl-28673988
ABSTRACT
Microtubules, the dynamic, yet stiff hollow tubes built from αß-tubulin protein heterodimers, are thought to be present only in eukaryotic cells. Here, we report a 3.6-Å helical reconstruction electron cryomicroscopy structure of four-stranded mini microtubules formed by bacterial tubulin-like Prosthecobacter dejongeii BtubAB proteins. Despite their much smaller diameter, mini microtubules share many key structural features with eukaryotic microtubules, such as an M-loop, alternating subunits, and a seam that breaks overall helical symmetry. Using in vitro total internal reflection fluorescence microscopy, we show that bacterial mini microtubules treadmill and display dynamic instability, another hallmark of eukaryotic microtubules. The third protein in the btub gene cluster, BtubC, previously known as "bacterial kinesin light chain," binds along protofilaments every 8 nm, inhibits BtubAB mini microtubule catastrophe, and increases rescue. Our work reveals that some bacteria contain regulated and dynamic cytomotive microtubule systems that were once thought to be only useful in much larger and sophisticated eukaryotic cells.
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MEDLINE
Assunto principal:
Proteínas de Bactérias
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Verrucomicrobia
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Microtúbulos
Idioma:
En
Ano de publicação:
2017
Tipo de documento:
Article