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(2008-07-20 21:37:27)
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[2008/06/24] ¹ÚÅ׸®¾Æ Æí¸ðÀÇ ¸ðÅÍ´Â ´Ü¹éÁú Ŭ·¯Ä¡¸¦ °¡Áö°í ÀÖ¾ú´Ù (Bacterial Flagellar Motor Has a Protein Clutch)
Bacterial Flagellar Motor Has a Protein Clutch   06/24/2008    
June 24, 2008 — The bacterial flagellum, the whiplike outboard motor that has become an icon of intelligent design, has another artificial-looking part: a clutch.  Science reported this in ¡°machine language¡± as follows:1
The bacterial flagellum, powered by a motor that generates 1400 pN-nm of torque, can rotate at a frequency of greater than 100 Hz.  EpsE [the clutch protein] disabled this powerful biological motor when associated with a flagellar basal body and, in a manner similar to that of a clutch, disengaged the drive train from the power sourcee (fig.  S5B).  Clutch control of flagellar function has distinct advantages over transcriptional control of flagellar gene expression for regulating motility.  Some bacteria, such as E. coli and B. subtilis, have many flagella per cell.  The flagellum is an elaborate, durable, energetically expensive, molecular machine and simply turning off de novo flagellum synthesis does not necessarily arrest motility.  Once flagellar gene expression is inactivated, multiple rounds of cell division may be required to segregate preexisting flagella to extinction in daughter cells.  In contrast, the clutch requires the synthesis of only a single protein to inhibit motility.  Furthermore, if biofilm formation is prematurely aborted, flagella once disabled by the clutch might be reactivated, allowing cells to bypass fresh investment in flagellar synthesis.  Whereas flagellum expression and assembly are complex and slow, clutch control is simple, rapid, and potentially reversible.
The clutch thus puts the flagellum in neutral and lets the motor idle without having to be shut down.  Among the co-authors of the paper was Howard Berg of Harvard, who has spent many years studying the molecular motor.  The paper did not attempt to explain how a clutch might evolve by natural selection.
    For popular reports on this finding, with illustrations of how the clutch works, visit NSF News, Nano.org, Photonics.com, PhysOrg and Science DailyARN discussed the paper from an intelligent design perspective.
1.  Blair, Turner, Winkelman, Berg and Kearns, ¡°A Molecular Clutch Disables Flagella in the Bacillus subtilis Biofilm,¡± Science, 20 June 2008: Vol. 320. no. 5883, pp. 1636 - 1638, DOI: 10.1126/science.1157877.
This is another of many instances of one of the best-established laws in nature: evolutionary storytelling is inversely proportional to observational detail.  A good scientific law needs a popular name.  Write in with your suggestion.

¹ÚÅ׸®¾Æ Æí¸ðÀÇ ¸ðÅÍ´Â ´Ü¹éÁú Ŭ·¯Ä¡¸¦ °¡Áö°í ÀÖ¾ú´Ù.
(Bacterial Flagellar Motor Has a Protein Clutch)
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2008³â 6¿ù 24ÀÏ - °íµµÀÇ ÁöÀû¼³°è·Î º¸ÀÌ´Â ¹ÚÅ׸®¾ÆÀÇ Æí¸ð(flagellum)´Â ¶Ç ÇϳªÀÇ ¼³°è·Î º¸ÀÌ´Â ÀåÄ¡·Î¼­ ÀÏÁ¾ÀÇ Å¬·¯Ä¡(clutch, ¿£ÁøÀÇ µ¿·ÂÀ» Àá½Ã ²÷°Å³ª À̾îÁÖ´Â ÃàÀÌÀ½ ÀåÄ¡)¸¦ °¡Áö°í ÀÖ¾ú´Ù. Science Áö´Â ¡®machine language¡¯¿¡¼­ À̰ÍÀ» ´ÙÀ½°ú °°ÀÌ º¸°íÇÏ¿´´Ù.[1] :

1400 pN-nmÀÇ È¸Àü·ÂÀ» ¹ß»ý½ÃŰ´Â ¸ðÅÍ(motor)¿¡ ÀÇÇØ¼­ µ¿·ÂÀ» ¾ò´Â ¼¼±ÕÀÇ Æí¸ð´Â 100 Hzº¸´Ù ´õ Å« ÁÖ±â·Î ȸÀüÇÒ ¼ö ÀÖ´Ù. EpsE(Ŭ·¯Ä¡ ´Ü¹éÁú)´Â Æí¸ð ±âÀúü(flagellar basal body)¿Í °áÇյǾúÀ» ¶§, ÀÌ °­·ÂÇÑ »ý¹°ÇÐÀû ¸ðÅ͸¦ ¹«·ÂÈ­½Ãų ¼ö ÀÖ¾ú´Ù. À̰ÍÀº Ŭ·¯Ä¡¿Í ¸Å¿ì À¯»çÇÑ ¹æ¹ýÀ¸·Î, µ¿·Â¿øÀ¸·ÎºÎÅÍ µ¿·ÂÀü´Þ °èÅëÀÇ ¿¬°áÀ» ¶¼¾î³»°í ÀÖ¾ú´Ù.(fig. S5B). Æí¸ð ±â´ÉÀÇ Å¬·¯Ä¡ Á¶ÀýÀº ¿îµ¿¼ºÀ» Á¶ÀýÇÏ´Â Æí¸ð À¯ÀüÀÚ ¹ßÇöÀÇ Àü»ç Á¶Àý(transcriptional control)¿¡ À־ ºÐ¸íÇÑ ÀÌÁ¡À» °¡Áö´Â °ÍÀÌ´Ù. ´ëÀå±Õ(E. coli)°ú °íÃʱÕ(B. subtilis)°ú °°Àº ¸î¸î ¹ÚÅ׸®¾ÆµéÀº ÇÑ ¼¼Æ÷¿¡ ¸¹Àº Æí¸ðµéÀ» °¡Áö°í ÀÖ´Ù. Æí¸ð´Â Á¤±³Çϰí, ³»±¸¼ºÀÌ ÀÖ´Â, µ¿·ÂÇÐÀûÀ¸·Î °íÈ¿À²ÀûÀÎ, ºÐÀÚ ±â°è(molecular machine)ÀÌ´Ù. ±×¸®°í ¿îµ¿À» Á¤ÁöÇϰíÀÚ ÇÒ ¶§, Æí¸ð ÇÕ¼ºÀ» óÀ½ºÎÅÍ ²¨¹ö¸± Çʿ䰡 ¾ø´Ù. Çѹø Æí¸ð À¯ÀüÀÚ ¹ßÇöÀÌ ºÒȰ¼ºÈ­ µÇ¸é, ÀÌ¹Ì Á¸ÀçÇÏ´Â Æí¸ðµéÀÌ ºÐ¸®µÇ¾î µþ¼¼Æ÷µé ³»¿¡¼­ ¼Ò¸êµÇ¾îÁú ¼öµµ ÀÖ´Ù. ÀÌ¿¡ ¹ÝÇØ, Ŭ·¯Ä¡´Â ¿îµ¿À» ¸ØÃß±â À§ÇØ ¿ÀÁ÷ ÇÑ ´Ü¹éÁúÀÇ ÇÕ¼º¸¸À» ¿ä±¸ÇÑ´Ù. ´õ±º´Ù³ª »ý¹°¸· Çü¼º(biofilm formation)ÀÌ ¼º¼÷µÇ±â Àü¿¡ À¯»êµÇ¾îÁø´Ù ÇÏ´õ¶óµµ, Ŭ·¯Ä¡¿¡ ÀÇÇØ¼­ Æí¸ð ÇÕ¼º¿¡ ´Ù½Ã Ãʱâ ÅõÀÚ¸¦ ÇÏÁö ¾Êµµ·Ï Çϸ鼭 ÇѶ§ ¹«·ÂÇØÁø Æí¸ðµéÀº ÀçȰ¼ºÈ­ ÇÒ ¼öµµ ÀÖ´Ù. ±×·¡¼­ Æí¸ðÀÇ ¹ßÇö°ú Á¶¸³Àº º¹ÀâÇÏ°í ´À¸®³ª, Ŭ·¯Ä¡ÀÇ Á¦¾î´Â °£´ÜÇϰí, ºü¸£°í, °¡¿ªÀûÀÏ ¼ö ÀÖ´Â °ÍÀÌ´Ù.

µû¶ó¼­ Ŭ·¯Ä¡´Â Æí¸ð¸¦ Á߸³ ±â¾î¿¡ ³õ¾ÆµÎ°í, ¿£ÁøÀÌ ²¨Áöµµ·Ï ÇÏÁö ¾ÊÀº ä ¸ðÅ͸¦ ½¬°ÔÇÒ ¼ö ÀÖ´Â °ÍÀÌ´Ù. ÀÌ ³í¹®ÀÇ °øµ¿ÀúÀÚµé Áß ÇÑ ¸íÀÎ ÇϹöµå ´ëÇÐÀÇ È£¿Íµå ¹ö±×(Howard Berg)´Â ÀÌ ºÐÀÚ ¸ðÅ͸¦ ¿¬±¸Çϱâ À§Çؼ­ ¼ö³â µ¿¾ÈÀ» ¼ÒºñÇØ¿Ô´Ù. ¾î¶»°Ô ±×·¯ÇÑ Å¬·¯Ä¡°¡ ¹«ÀÛÀ§ÀûÀÎ µ¹¿¬º¯ÀÌ¿Í ÀÚ¿¬¼±ÅÃÀ» ÅëÇØ ÁøÈ­µÇ¾îÁú ¼ö ÀÖ¾ú´ÂÁö, ±× ³í¹®Àº ±× ¾î¶°ÇÑ ¼³¸íµµ ÇÏÁö ¾Ê°í ÀÖ¾ú´Ù.

¾î¶»°Ô ±× Ŭ·¯Ä¡°¡ ÀÛµ¿µÇ´Â Áö¿¡ ´ëÇØ¼­´Â NSF News, Nano.org, Photonics.com, PhysOrg, Science Daily µîÀ» Ŭ¸¯ÇÏ¿© »ìÆìº¸¶ó. ARNÀº ÁöÀû¼³°è(intelligent design) Ãø¸é¿¡¼­ ±× ³í¹®À» ´Ù·ç°í ÀÖ¾ú´Ù.

[1] Blair, Turner, Winkelman, Berg and Kearns, 'A Molecular Clutch Disables Flagella in the Bacillus subtilis Biofilm,¡± Science, 20 June 2008: Vol. 320. no. 5883, pp. 1636 - 1638, DOI: 10.1126/science.1157877.

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À̰ÍÀº ÀÚ¿¬¿¡¼­ µå·¯³ª°í ÀÖ´Â ³î¶øµµ·Ï º¹ÀâÇÏ°í °æÀÌ·Î¿î »ç·Êµé Áß¿¡ ¶Ç ÇϳªÀÇ »ç·ÊÀÌ´Ù. ÁøÈ­·ÐÀÇ µ¿È­ °°Àº À̾߱â´Â °üÃøµÇ´Â »ç½Çµé°ú Á¡Á¡ ´õ ¸Ö¾îÁö°í ÀÖ´Ù. ÀÌ·¯ÇÑ ¸ÚÁø °úÇÐ ¹ýÄ¢Àº ÇϳªÀÇ ´ëÁßÀû ¸íĪÀ» ÇÊ¿ä·Î Çϰí ÀÖ´Ù. ´ç½ÅÀÇ ÀǰßÀ» À̰÷À¸·Î(Write in) º¸³»´Þ¶ó.

Ãâó : Creation-Evolution Headlines, 2008. 6. 24.
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