Centromere and kinetochore structure

POKRYWKA NJ, STEPHENSON EC: Microtubules Mediate the Localization of Bicoid RNA During Drosophila Oogenesis. Development 1991, 113:55-66. Microtubules are shown to be a major component in bicoid mRNA localization by studies using colchicine and taxol. This work is particularly interesting because it uses the various mutants to assess the role of these drugs and reveals that the SWW mutant, incapable of localizing bicoid can be induced to localize when exposed to taxol.

Centromere and kinetochore structure by William C. Earnshaw and John E. Tomkiel HAD~C~KY G, PRAZNOWZKYT, CSERpiw I, KERESOJ, P&ERW M, KELEMYEN I, ATALAY E, SZELES A, SZELEI J, TUEUK V, BURG K: Centromere Formation in Mouse Cells Cotransformed with Human DNA and a Dominant Marker Gene. Proc Natl Acad Sci USA 1991, 88:8106-8110. Generation of a stable minichromosome in mouse after transfection with a 13.8.kb putative human centromere sequence. This work may represent the lirst identification of CEN sequences in mammals. LECHNFCRJ, CARBON J: A 240 kd Multisubunit

Protein Complex, CBF3, is a Major Component of the Budding Yeast Centromere. Cell 1991, 64717-725. A biochemical tour de force. Isolation of CBPIII, a 240. kd multisubunit factor that binds the critical CDEIII sequence of the S. cerevtiiae centromere. The binding of CBFm is shown to be dependent on both phosphorylation and the presence of an assembly co-factor. KINGSBURY J, KOSHLAND D:

Centromere-dependent Binding of Yeast Minichromosomes to Microtubules in Vitro. Cell 1991, 6Qi83-495. The development of an in vitro assay for the binding of microtubules to centromeres in S. cereviside. This work delimits the CEN sequences required to bind microtubules (CDEII and CDEIII, but not CDEI), and presents a means of identifying genes required in this step. CelLcy cle regulation of microtubule binding is suggested by the finding that CEN DNA from G2-M-arrested cells is more efficient at microtubule binding than CEN DNA from Glarrested cells. This is potentially a powerful assay for clissetting assembly and regulation of centromeres.

Microtubule

dynamics

by Michael

Caplow

GOTOH Y, NISHIDA E, MATXJDA S, WIINA N, KOSAKO H, SHIOKAWA K, AKIVAMAT, KUNIHIRO 0, SAKAIH: In Vitro

Effects on Microtubule Dynamics of wed Xenopus M Phase-activated MAP Kinase. Nature 1991, 349:251-254. MAP-2 kitie, which is activated during M phase of meiotic and mitotic cells, was purified from Xenopuseggs and found to modify dynamic behavior of microtubules in interphase extracts. The kinase reduced the apparent growth rate and decreased the mean steady-state microtubule length to a level seen with metaphase II extracts. 156

intermediate filament structure by David A.D. Parry and Peter M. Steinert O’SHEA EK, KLEMM JD, KIM PS, ALBERT T: X-ray Struc-

ture of the GCN4 Leucine Zipper, a Two-stranded, Parallel Coiled-coil. Science 1991, 254:539-544. This paper reports the first high-resolution structure of a (two-stranded) coiled-coil structure. As such it provides details on the packing of apolar residues along the axis of the structure and the formation of the interchain ionic interactions that specify relative chain polarity and axial stagger. It coniirms previous theoretical analyses and provides strong experimental evidence that the structure of the rod domain of IF molecules is as predicted. BONIF% JM, ROTHMAN AL, EPSTEIN EH: Epidermolysis Bullosa Simplex: Evidence in Two Families for Keratin Gene Abnormalities. Science 1991, 254:1202-1205. This pioneering paper is the first to show that a simple single-point mutation in the rod domain of K14, expressed in the basal cells of human epidermis, may be the proximal cause of the blistering skin disease, EBS. This is an example of the use of classic genetic linkage analyses, followed by sequencing of candidate genes that ultimately identified the mutation. In addition, the EBS phenotype in another affected family is reported to map to the 12q type II keratin locus, suggesting that mutations in K5 (the other keratin chain expressed in basal epidermal cells) may cause a similar disease.

Axonemal

dyneins

by George B. Witman

Identification of oda6 as a Dynein Mutant by Rescue With the Wild-type Gene. J Cell Biol 1991, 113:835--842. A landmark paper in which genetic transformation is used to identify a mutated gene product resulting in the absence of the outer arm. Also reports the deduced amino acid sequence of the 69%~ intermediate chain of outer-arm dynein and demonstrates that this chain is important in outer-arm assembly. MITCHELL DR, KANG Y:

Chlamydomonas

SAKAIOBARA H, MITCHELL DR, KAMWA RI A Chlamy domonas Outer-arm Dynein Mutant Missing the c1Heavy Chain. J Cell Biol 1991, 113:615-622. The first identification of a mutation that prevents assembly of one outer-arm component without affecting assembly of the other outer-arm components. Shows that the 01 heavy chain forms the outermost electron density of the outer arm, and that the absence of this chain impairs arm function only partially. I KURIMOTO E, KAMWA R: Microtubule

Sliding in Flagellar Axonemes of Chlamydomonas Mutants Missing Inner or Outer-arm Dynein: Velocity Measurements on New Types of Mutants by an Improved Method. Cell Motil Cytoskeleton 1991, 19:275-281. By studying microtubule sliding in disintegrating axonemes, the authors obtained evidence that the inner and outer arms drive microtubules at different rates, and that the inner arms are important for the initiation of sliding. @ 1992 Current

Biology