Dissolve yeast and 1 teaspoon sugar in warm water, stirring well. Let stand 5 minutes or until bubbly.
Cream 1/2 cup margarine in a large mixing bowl; gradually add remaining sugar and salt, beating well. Scald non-dairy creamer; let cool to 105° to 115°. Add non-dairy creamer, yeast mixture, eggs, and 1 yolk, stirring well. Gradually add 2 cups flour, beating well. Stir in remaining 1 1/4 cups flour (dough will be sticky).
Place dough in a well-greased bowl, turning to grease top. Cover and let rise in a warm place (85°), free from drafts, 1 hour or until doubled in bulk. Stir dough down. Cover and refrigerate dough for at least 4 hours.
Punch dough down; let rest 5 minutes. Divide dough in half. Divide one half into 3 equal portions; set aside remaining half. Shape each portion into a 10- inch rope. Braid ropes, pinching ends to seal. Place braided loaf in a greased 8-inch loaf pan. Repeat procedure with remaining half of dough. Cover and repeat rising procedure 1 hour or until doubled in bulk.
Combine remaining yolk and 2 tablespoons water; beat well. Gently brush over tops of loaves. Bake at 350° for 20 minutes or until loaves sound hollow when tapped. Remove bread from pans immediately, and cool on wire racks. Slice and serve warm.