Kojima Group

Bacterial flagella: morphogenesis and function of the motility organ

Welcome to Kojima Group - we study bacterial flagellar motility

“Cell motility” is the most fundamental biological process. Our lab studies the mechanisms of motility, especially focusing on the unicellular microorganisms, named bacteria. Most of the motile bacteria move by using the motility organ, known as the flagellum. Bacteria swim in liquid environment by rotating flagellar filaments, which is driven by a rotary motor at its base embedded in the cell surface. The flagellar motor is tiny rotary machinery in living cells with a unique energy conversion mechanism driven by the electrochemical gradient of ions across the cell membrane. However, many mysteries remain: 1) how does the motor convert ion-motive force to mechanical force?, 2) how do cells control the rotational speed and direction of the motor? 3) how does cells determine the number of flagellar numbers and placement sites at the cell body?

To elucidate above three questions, we conduct researches using methods of molecular biology (mutant analysis), cell biology (protein localization), biochemistry (protein purification and activity measurement), biophysics (measurement of motility and rotation), and structural biology, in collaboration with other laboratories in Japan and foreign countries. We approach questions like "how does a cell move?", "how are molecules properly positioned at appropriate time with suitable number?" Unicellular and rapidly growing bacteria are advantageous to address such fundamental questions in life science.

Shown below are introductory illustrations of our group is working on. See also the motility movie below!

Movies of bacterial flagellar motility. A: polar flagellar motility (strain NMB136), B: polar flagellar motility with multiple flagella at cell pole (strain KK148). High intensity of dark-field microscope can detect flagellar bundles at pole, C: lateral flagellar motility (strain YM19).

NMB136_swimming.mpg

A: Swimming of NMB136 cells

KK148_swimming.mpg

B: Swimming of KK148 cells

YM19_swimming.mpg

C: swimming of YM19 cells

YM19_tethered cell.mpg

Rotation of flagellar motor at its base can be visualized by the method named "tethered cell". Only single flagellum is fixed on the glass surface by an antibody of flagella. In this condition, the motor cannot rotate fixed flagellum, but instead rotate the cell body.

Introduction of bacterial flagellar motility (J)

(movie generated by

School of Science, Nagoya University)

Group introduction_to students

Our group, "Group of Microbial Motility", is run by two scientists; Dr. Seiji Kojima (principal investigator and professor, G30 program) and Dr. Kentaro Noma (associate professor, G30 program). We both had experience to live in USA for several years. Our lab consists of two sub groups: Kojima group, working on bacterial flagellar motility, and Noma group, working on heghaviral aging of worm. Seiji and Ken are in charge of G30 international program for Biology program (school of science, shorten name is "BioSci"), and teach lecture courses for G30 students both undergraduate and graduate students. Seiji is also in charge of the exchange program between University of Manchester and Nagoya University for one year.

For information of G30 international program, see the link below:

G30 International Program of Nagoya University

We have a joint group meeting once a week together, and share the room for students (G409), and the room for staff (G411). Experimental laboratories are separated, but we closely communicate and help each other, to function as one group. Kojima group meeting will be done once a week (project meeting and journal club). We use English as a common language for lab meeting. However, Seiji is flexible to use both languages so no worries if you are not good at speaking English. Seiji welcomes students who enjoy experiments, reading scientific papers, and curious to scientific questions. No specific experience is needed.

Shown below are some lab equipments for conducting experiments.